Do Routine Mammograms Save Lives?

Check out this answer from Consensus:

Routine mammograms do save lives, but the extent of their benefit varies depending on age and individual risk factors. While they are effective in reducing breast cancer mortality, especially in older women, the risks of false positives, overdiagnosis, and radiation exposure must be carefully weighed. It is crucial for women to be well-informed about both the benefits and risks of mammography to make an educated decision about their screening practices.

Mammography has long been a cornerstone of breast cancer screening, with the primary goal of reducing mortality through early detection. However, the effectiveness and benefits of routine mammograms have been subjects of ongoing debate. This article aims to explore whether routine mammograms save lives by examining various research findings.

Benefits of Routine Mammograms

Reduction in Breast Cancer Mortality

Several studies have demonstrated that routine mammograms can reduce breast cancer mortality. For instance, a randomized controlled trial estimated that screening 465 women over seven years could save one life over a 20-year follow-up period3. Another study found that repeated screening starting at age 50 saves about 1.8 lives per 1000 women screened over 15 years1. These findings suggest that mammography is effective in reducing breast cancer deaths, albeit the absolute benefit may be modest.

Long-term Benefits

Long-term follow-up studies have provided more accurate estimates of the benefits of mammography. For example, a study involving a 29-year follow-up in Sweden showed a significant decrease in breast cancer deaths among women who participated in screening6. This long-term data supports the notion that routine mammograms contribute to a reduction in mortality rates.

Risks and Controversies

False Positives and Overdiagnosis

One of the significant risks associated with routine mammograms is the high rate of false positives. Approximately 8% of screening mammograms in the U.S. are found to be abnormal, but fewer than 10% of these cases actually have breast cancer2. False positives can lead to unnecessary anxiety, additional procedures, and even biopsies, which occur in about 25% of false-positive cases2. Overdiagnosis is another concern, with estimates suggesting that about 70,000 U.S. women per year are overdiagnosed, leading to unnecessary treatments7.

Radiation Risks

Although the radiation risk from mammography is considered extremely small, it is not negligible. A study estimated that annual mammography of 100,000 women for 10 consecutive years beginning at age 40 could result in at most eight breast cancer deaths due to radiation exposure4. However, the benefits of screening, such as a 24% reduction in mortality from biennial screening, far outweigh these risks4.

Effectiveness in Different Age Groups

The effectiveness of mammography varies by age group. For women aged 40-49, the benefits are less clear compared to older age groups. A study found that the relative risk reduction in breast cancer mortality for women aged 40-60 was about 11%, which translates to a very modest absolute benefit2. In contrast, the life-saving absolute benefit of screening mammography increases with age, as the absolute death risk from breast cancer rises1.

 

---

Do routine mammograms save lives?

Archie Bleyer has answered Unlikely

An expert from Oregon Health & Science University in Oncology, Paediatrics, Radiology

As exemplified by the replies on this Metafact page, the answer remains contentious. Of the 37 responses to date (August 1), 30 contend that saving lives is likely or almost certain and 7 opine unlikely or extremely unlikely. Virtually all of the 30 affirmative responses are limited to breast cancer mortality and do not consider overall mortality (death due any cause, all-cause-related mortality). All-cause mortality is mentioned in only two replies.

As alluded to by some of the respondents, the best source of evidence for both breast cancer and overall mortality are the eight prospective randomized controlled trials of screening mammography that were conducted 30 to 55 years ago in North America and Europe and one more conducted 20 to 30 years ago. A total of more than 430,000 women were randomized.

Seven of the eight trials showed a reduced rate of breast cancer deaths, of which 4 were statistically significant. None of them, however, reported an overall mortality reduction. One of them reported an identical overall mortality up to 25 years after randomization. All the others followed the patients long enough to detect a reduction in breast cancer mortality, of which four reported a statistically-significant reduction in breast cancer mortality. If overall survival remained static when breast cancer deaths decreased, there must have been an increase in deaths due to other causes than breast cancer that was comparable to the reduction in breast cancer deaths per se.

Some of the trials were evaluated too early to ascertain an ultimate benefit in overall mortality reduction. These trials did, however, report a decrease in breast cancer mortality benefit when they were evaluated and yet had at the same time no difference in overall mortality. There had to be, by then, an excess of deaths due to other causes than breast cancer.

Why hasn’t all-cause mortality declined due to the reductions claimed in breast cancer mortality? What were the other causes of deaths? The randomized trial reports generally lack detail on the other deaths, except for the best known mortality risks of radiation and chemotherapy, such as second malignant neoplasm or cardiovascular deaths. Other possible causes of death include: chemotherapy-related immunosuppression, myelosuppression, infections, liver failure, kidney dysfunction or gastrointestinal disease;1 radiation-induced lung damage;1 pathologic bone fractures due to antiestrogen therapy; suicide1 as a result of decreased quality of life associated with the diagnosis of breast cancer and/or treatment as is known to occur with mastectomy, hormone therapy, chemotherapy and radiotherapy.

Whatever the causes of excess non-breast-cancer deaths, the lack of overall mortality reduction in the presence of decreased breast cancer mortality can only occur if women with screen-detected cancers had a higher death rate from other causes than age-matched women. Yet, the totality of randomized trials has been interpreted to indicate that screening is so good we can ignore the deaths due to other causes.

Increased early detection, increased percentage of early stage tumors, and improved breast cancer survival rates cannot be used ipso facto to prove that screening saves lives. Yet, in a national sample during 2010-2011, 47% of 412 U.S. primary care physicians mistakenly believed that if more cancers are detected by a screening test, this proves that the test saves lives, and 76% wrongly thought that if screen-detected cancers have better 5‑year survival rates than cancers detected by symptoms, this also proves that the screening test saves lives.(2)

Screening mammography does save some women from dying of breast cancer but for others it just changes the cause of their death. Screening may bring women to healthcare settings where they can access life-saving medical care they otherwise would not receive, but the screening mammography itself would not result in a longer life. On the contrary, the totality of evidence is that screening mammography results in a death rate from other causes that negate the breast cancer mortality reduction. And, depending on the other cause, the suffering may be greater than that associated with dying of breast cancer, such as depression leading to suicide, enduring chronic lung or heart failure, or developing a worse cancer.

Archie Bleyer, MD, Bend, Oregon

Oregon Health and Science University, Oncology

 Rebecca H. Johnson, MD, Seattle, Washington

Mary Bridge Children’s Hospital, Oncology

 Cornelia J. Baines, MD, MSc, FACE, Toronto, Ontario

University of Toronto, Public Health

 Anthony B. Miller, MD, Toronto, Ontario

University of Toronto, Epidemiology

 

1.   Riihimäki M, Thomsen H, Brandt A, Sundquist J, Hemminki K. Death causes in breast cancer patients. Ann Oncol. 2012 Mar;23(3):604-610
2.   Wegwarth O, Gigerenzer G. The barrier to informed choice in cancer screening. Recent Results Cancer Res. 2018;210:207-221.

 

Do routine mammograms save lives?

Kenneth Foster has answered Near Certain

An expert from University of Pennsylvania in Biomedical Engineering

Answer is yes but…

a previous respondent (Tom Marshall) cited a 2013 Cochrane review.

A more recent systematic review and meta-analysis (see cite below) concluded:

“Breast cancer mortality is generally reduced with mammography screening, although estimates are not statistically significant at all ages and the magnitudes of effect are small. Advanced cancer is reduced with screening for women aged 50 years or older.”

Effect size (from the paper):

women aged 39-49 : 3 deaths prevented per 10 000 women over 10 years;

aged 50 to 59 years: 8 deaths prevented per 10 000 women over 10 years;

aged 60 to 69 years: 21 deaths prevented per 10 000 women over 10 years;

aged 70 to 74 years: 13 deaths prevented per 10 000 women over 10 years.

authors conclusion:

• Risk reduction was 25% to 31% for women aged 50 to 69 years in observational studies of mammography screening.

• All-cause mortality was not reduced with screening

But note that most of the studies reviewed involved now-outdated imaging technology.

These benefits need to be considered against what many experts consider to be overdiagnosis: diagnosis and treatment of breast cancer that would otherwise not have become a threat to their health during their lifetime. As with everything else about mammography, the tradeoffs between early detection and overdiagnosis are controversial and to a large extent a matter of individual judgment.

So according to the best available evidence, mammography saves lives (more precisely reduces deaths from breast cancer), but it is certainly not a magic bullet.

ref: Nelson, Heidi D., et al. “Effectiveness of breast cancer screening: systematic review and meta-analysis to update the 2009 US Preventive Services Task Force recommendation.” Annals of internal medicine 164.4 (2016): 244-255.

see also

Siu, Albert L. “Screening for breast cancer: US Preventive Services Task Force recommendation statement.” Annals of internal medicine 164.4 (2016): 279-296.

 

Do routine mammograms save lives?

Paul Glasziou has answered Likely

An expert from Bond University in Medicine

Probably, but the downsides need to be considered also, particularly the problem of “overdiagnosis”. With 10 randomized trials of breast screening spanning 4 decades, there a substantial body of evidence, but with different aims and flaws https://www.ncbi.nlm.nih.gov/pubmed/21658406. Combined analysis of the intention-to-treat results gives an overall relative reduction in breast cancer mortality of 19% (95% CI 12%–26%), which, if adjusted for non-attendance gives an approximate 25% relative reduction for those who attend screening. 

However, given that 4% of all-cause mortality is due to breast cancer deaths, this translates into a less than 1% reduction in all-cause mortality, which is too small to be detected reliably by the trials. For every live (possibly) saved there are probably 5 women who are overdiagnosed and unnecessarily treated. A good summary of this dilemma is at: https://www.harding-center.mpg.de/en/fact-boxes/early-detection-of-cancer/breast-cancer-early-detection

 

Do routine mammograms save lives?

Ashkan Ghanbarzadeh Dagheyan has answered Unlikely

An expert from Northeastern University in Breast Cancer

That is yet a complex question because we do not have enough and certain population-based, unbiased evidence to be able to make a conclusion. There are reviews such as [1] and [2] that argue that in overall the use of mammograms has been able to reduce breast cancer mortality; yet, the major, inherent problems of mammography make such conclusion uncertain.

These main problems are false-positive results [3], false negative results [4], ionizing radiation [5], and overdiagnosis [6-8]. False-negative and -positive results inhibit accurate detection; the former cause radiologists’ missing an existing tumor and the later shows the presence of a false tumor, leading to unnecessary biopsies, and distress for patients for months, sometimes up to two years. However, ionizing radiation and overdiagnosis have different consequences in nature: ionizing radiation over years can be a contributing factor in breast cancer development itself and overdiagnosis, which is finding sub-clinical or non-advanced breast cancers, casts doubt on the effectiveness of mammography.

Considering overdiagnosis and other drawbacks of mammography, even though some studies have made an effort to exclude the effect of advanced methods of treatment on the reduction of breast cancer mortality to find the independent impact of screening on breast cancer death rate [9], still it is difficult to decide whether mammography’s role in saving lives significantly outweighs its role in causing serious problems for patients.

It is also particularly important to note that computing mortality rates depends in incidence rates and the rise in breast cancer incidence globally might be due to two main contributors: (1) finding too many cancers by mammography, and/or (2) unhealthy, western diet and lifestyles that lead to mammary carcinogenesis and other cancers. We will not know which one of these is the main factor unless we conduct vast autopsy studies to find out how many of the deaths in a specific time span have been due to breast cancer. If the rate were high, we would know that the incidence has really increased and so mortality rate estimations could be correct; if not, we would know that we are finding too many non-life-threatening breast cancers and so our estimate of mortality rates must also be revised.

I selected the “unlikely” response, because my studies of tens of papers have created a doubt in me about the efficacy of mammography. If there were a button stating “unknown yet”, I would have selected that. Mammography saves some lives, but we need a lot more evidence, by independent organizations and researchers who do not benefit from the breast cancer detection enterprise, to understand whether the benefits significantly surpass the harms.

[1] American Cancer Society. Breast Cancer Facts & Figures 2013–2014; American Cancer Society, Inc.: Atlanta, GA, USA, 2013.

[2] Independent UK Panel on Breast Cancer Screening. “The benefits and harms of breast cancer screening: an independent review.” The Lancet 380.9855 (2012): 1778-1786.

[3] Hubbard, Rebecca A., et al. “Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study.” Annals of internal medicine 155.8 (2011): 481-492.

[4] Warren Burhenne, Linda J., et al. “Potential contribution of computer-aided detection to the sensitivity of screening mammography.” Radiology 215.2 (2000): 554-562.

[5] Brenner, David J., et al. “Cancer risks attributable to low doses of ionizing radiation: assessing what we really know.” Proceedings of the National Academy of Sciences 100.24 (2003): 13761-13766.

[6] Zackrisson, Sophia, et al. “Rate of over-diagnosis of breast cancer 15 years after end of Malmö mammographic screening trial: follow-up study.” Bmj 332.7543 (2006): 689-692.

[7] Duffy, Stephen W., et al. “Absolute Numbers of Lives Saved and Overdiagnosis in Breast Cancer Screeninq, from a Randomized Trial and from the Breast Screening Programme in England.” Journal of medical screening 17.1 (2010): 25-30.

[8] Puliti, Donella, et al. “Overdiagnosis in mammographic screening for breast cancer in Europe: a literature review.” Journal of medical screening 19.1_suppl (2012): 42-56.

[9] Olsen, Anne Helene, et al. “Breast cancer mortality in Copenhagen after introduction of mammography screening: cohort study.” Bmj 330.7485 (2005): 220.

 

Do routine mammograms save lives?

Martin Yaffe has answered Near Certain

An expert from University of Toronto in Oncology

There have been 8 major randomized trials of the efficacy of mammography screening for women between ages 40 and 74 as well as studies of the actual impact of screening programs in several Western countries, including Canada (J Natl Cancer Inst). Multiple analyses by experts at the international Agency for Research on Cancer (WHO), The American Cancer Society, The Independent UK Study examined all of the data from the randomized trials and concluded that mammographic screening reduces breast cancer mortality.

The Pan Canadian (Coldman et al) study showed that there were 30%-44% fewer breast cancer deaths in women who participated in screening programs. That study showed similar benefits for women beginning at age 40There is also evidence that women whose cancer are detected by screening are less likely to require mastectomy or chemotherapy and more likely to have smaller cancers free from lymph node metastasis (Barth et al 2005). A more recent study performed at Mt. Sinai Hospital in New York with similar findings is described in this article.

The benefit from screening almost certainly comes from the synergy rather than a competition between between earlier detection provided by the screening allowing therapies to be more effective on these cancers. Therapies, screening and diagnostic methods have improved tremendously during the past 20 years (e.g. digital mammography, image-guided, core biopsy ,the drug herceptin and aromatase inhibitors) so the randomized trials, conducted decades ago in the days of film mammography, more primitive imaging systems and fewer therapeutic options, probably underestimate the mortality reduction.

The decision about screening should be a woman’s personal one, based on solid science and on her preferences and values regarding risk. Most (88%) women won’t develop breast cancer, but 12% will. Most women who get breast cancer won’t die from it, but about 1/3 of the women who get breast cancer will. Importantly, the chances of surviving breast cancer and of requiring less aggressive and toxic therapies are higher when cancers are detected earlier through screening.

The downside is that mammography screening can find most but not all cancers (MRI screening is recommended for women at the highest risk), some women will be called back for more imaging after screening even if they don’t have cancer (short term stress) and some breast cancers may not be lethal, but we don’t know in advance which these are, at least until they are removed, and sometimes, even then, this is not clear. So, perhaps rather than deciding not to be screened because of this possible “overdiagnosis”, if a cancer is detected by screening, a woman should carefully review treatment options with her health provider to avoid overtreatment.

In summary, there is compelling evidence regarding the benefits of screening, but women should also appreciate that it has limitations. Unfortunately, in the past few years some have overstated these limitations, for reasons that I suspect go outside of science.

 

Do routine mammograms save lives?

Nancy Keating has answered Likely

An expert from Harvard University in Medicine

Likely that it decreases the risk of dying of breast cancer; uncertain about decreasing risk of dying of all causes.

The strongest evidence for mammography screening is based on randomized clinical trials conducted in the 1960s to 1990s and suggest a relative risk reduction of breast cancer mortality of about 19%, but that varies by age from about 8% for women in their 40s to 33% for women in their 60s. However, the absolute risk reduction is quite low, as summarized below and in the Nelson meta-analysis (Annals, 2016). Our estimates are that breast cancer specific mortality benefit translates to

~3 lives saved per 10,000 women in their 40s

~10 lives saved per 10,000 women in their 50s

~43 lives saved per 10,000 women in their 60s

The key reason this question has received so much attention is that the benefit, especially for younger women, is very small, and we are increasingly aware of the risks of mammography, which include false positive mammograms, unnecessary biopsies, and overdiagnosis–where we diagnose cancers that would never become clinically evident in a woman’s lifetime in the absence of screening. However, since we can’t tell which cancers are overdiagnosed and which are not, we treat them all, subjecting some women to the harms of treatment without benefit.

Decisions about mammography should incorporate assessment of a woman’s individual risk of getting cancer as well as summary of the benefits and harms in the context of her values and preferences. A supplement that is part of this paper includes some decision tools that can help women make decisions about mammography screening:

Keating & Pace, Breast Cancer Screening in 2018: Time for Shared Decision Making. JAMA 2018; 17: 1814-1815.

 

Do routine mammograms save lives?

A Lucassen has answered Unlikely

An expert from University of Southampton in Genetics, Philosophy, Oncology

Probably do not save lives, even if lead to earlier detection.

beautifully depicted in info graphic here:https://www.harding-center.mpg.de/en/fact-boxes/early-detection-of-cancer/breast-cancer-early-detection

 

Do routine mammograms save lives?

Tom Marshall has answered Unlikely

An expert from Birmingham University in Epidemiology

The most comprehensive review of high quality evidence was undertaken by the Cochrane group. They found eight randomised controlled trials. Some of these have methodological problems (the groups offered and not offered mammography screening were systematically different before the trial started). When only the highest quality trials are considered there is no evidence of a reduction in overall mortality. When the lower quality trials are included there was a small reduction in breast cancer mortality but no effect on all cause mortality. They found that significantly more women offered mammography screening underwent breast surgery.

The randomised controlled trials of mammography screening were carried out between 27 and 40 years ago. Since then the treatment of breast cancer has greatly improved, so any benefits from earlier detection are likely to be more modest today than at the time of the trials.

If mammography screening were a drug it would probably not be granted a licence on the basis of this evidence. Many individuals have careers invested in delivering mammography screening or researching mammography screening or have strong emotional or political reasons for wanting to believe that it is effective. In such circumstances it is very difficult to challenge prevailing wisdom.

 

Do routine mammograms save lives?

Harmen Bijwaard has answered Near Certain

An expert from Netherlands National Institute for Public Health and the Environment in Physics

There’s a lot of research in this area, some of it pointing in other directions, but I think the most convincing evidence comes from the reduction in mortality from breast cancer that can be observed after the introduction of mammography screening. In the Netherlands (where I’m based) this reduction is more than 25%. Some of it is probably due to improved treatment, but for a large part it is the earlier detection that allows for better treatment options and hence the decrease in mortality.

 

Do routine mammograms save lives?

Don Benjamin has answered Extremely Unlikely

An expert from Cancer Information & Support Society in Health, Statistics, Medicine

The question of “Do regular mammograms save lives?” should be answered with a definitive No.

Many randomised controlled trials have evaluated the potential benefits of mammography screening, ie regular mammograms for healthy women. None of the seven trials identified any significant benefit in terms of a reduction in overall mortality, but most trials identified significant levels of overdiagnosis and overtreatment. That is about one in three women identified as having breast cancer were then treated for it unnecessarily ‘just in case’. In other words mammography screening results in significant harm but no proven significant benefits. In this context ‘significant benefits’ means a reduction in deaths that is greater than chance at a 95% confidence level.

The reason many surgeons and researchers incorrectly claim that mammogram screening saves lives comes from a widespread misunderstanding of the rules of running randomised controlled trials and interpreting their results. For example the two basic rules of such trials is that

1. You are only allowed to change or add one treatment in the group being studied (those offered screening) compared to the matched control group (not offered screening); and
2. You can only compare the deaths in the whole study group with those in the whole control group. You are not permitted to compare sub-groups within the trial as these are no longer comparisons between matched groups.

Both of these rules were ignored in all of the trials. For example the protocols used required that women who had breast cancer identified earlier by screening were given more radiotherapy and those with breast cancer identified later were given more chemotherapy. This meant that both radiotherapy and chemotherapy were given differently to the two matched groups.

The main factor being measured by the trial was supposed to be benefits of the earlier surgery made possible by the earlier detection of breast cancer from the mammogram compared with the later surgery experienced by those not offered screening. Instead the trials confounded the results of the potential benefits of this earlier surgery with uneven numbers of deaths resulting from the radiotherapy and chemotherapy in the two groups. For example there were typically more cardiovascular deaths from radiotherapy in the screened group (and therefore fewer deaths from breast cancer) than in the control group leading to the incorrect claim that mammograms reduced the breast cancer deaths by up to 20 percent.

Comparing deaths from all causes between the two groups overcomes this common flaw in interpretation of results. I pointed this out in my 1996 paper on the efficacy of breast cancer surgery.

Similar screening has been evaluated for bowel, lung, prostate and ovarian cancer. In all cases there was no significant benefit observed when deaths from all causes were compared.  A more recent trial evaluating a new type of lung cancer screening that claimed a reduction in deaths from all causes of 7 percent included several methodological flaws. I have recently submitted a paper for publication outlining these flaws.

If earlier surgery has not be found to reduce deaths in any of these five types of cancer it is time to question the hypothesis on which cancer surgery is based:  cancer starts locally and later spreads; so earlier surgery gets the cancer before it has spread. This and emerging evidence suggests an alternative cancer paradigm or hypothesis:  cancer is already a systemic disease when first diagnosed.

 

Do routine mammograms save lives?

Anthony B.  Miller has answered Unlikely

An expert from University of Toronto in Epidemiology

I recently wrote a review article on this question concluding “we have reached the point of negligible benefit from mammography screening for breast cancer in women at average risk, and that we should concentrate on early diagnosis of breast cancer and the application of modern therapy according to clearly defined sub-types of breast cancer.”

Here are the details and source of the paper:

https://www.tandfonline.com/doi/abs/10.1080/13697137.2017.1392503?tab=permissions&scroll=top

 

Do routine mammograms save lives?

Cornelia  Baines has answered Unlikely

An expert from University of Toronto in Epidemiology, Oncology, Global Health

Please see this answer from Archie Bleyer MD – of which I reviewed and concur with.

 

Do routine mammograms save lives?

January Lopez has answered Near Certain

An expert from Hoag Hospital in Medicine, Radiology

Mammograms undoubtedly save lives. The controversy is over how many and whether those lives are worth the “costs“. Consensus regarding those questions is a near impossibility because:

1) The data on screening mammography is imperfect and requires a significant degree of “interpretation” and assumption in order to draw conclusions, which are inherently limited. For example, randomized controlled trials that are still used in the assessment of mammography (some performed over half a century ago!) analyze mortality rates between groups of women who are invited and not invited to undergo screening. An intention to treat analysis underestimates the benefit of mammography because of contamination (women ‘not invited’ undergo screening) and non-compliance (‘invited’ women don’t get screened).

Long term follow-up data also shows that breast cancer specific mortality reduction continues even at 29-years following intervention. https://pubs.rsna.org/doi/full/10.1148/radiol.11110469. Much of the data cited in the discussion of screening mammography involves studies and/or analyses of short term follow-up data of less than 10 years, even 1 or 2-years follow-up. This is too short to make meaningful conclusions about mortality benefit.

These are just two of many examples of how screening mammography data is limited.

2) New, better, large-scale randomized controlled trial data looking at mortality benefit from screening mammography is highly unlikely in the future. In decades past, these studies were possible because mammography was not established as a standard of care. Withholding mammogram screening was ethical back in the 60’s and 70’s, but this is no longer feasible or ethical today.

3) Accurately quantifying the “costs” of breast cancer screening is impossible, regardless of the tools and modeling used in the current literature. Many of these costs are subjective, unmeasurable, and/or widely variable…anxiety, pain from a biopsy, etc. “overdiagnosis” of breast cancer is also a hotly debated “cost” that is nearly as controversial as the topic of screening mammography itself. Regardless of the quantification of overdiagnosis, the fact is that today, there is no way to reliably or accurately determine whether any given breast cancer will or will not be fatal if left untreated. Perhaps someday…not today.

The bottom line is that the data on screening mammography is too imperfect/unclear and the quantification of costs/benefits too complex and subjective to reach a consensus on the cost/benefit discussion. With such uncertainty it behooves us to take a step back and look at the fundamental, common sense perspective. Despite our modern advances in treatment and screening, breast cancer remains the 2nd leading cause of cancer deaths among women. We know that screening mammography leads to earlier detection, and that breast cancer survival correlates with earlier stage. https://seer.cancer.gov/statfacts/html/breast.html

 

Do routine mammograms save lives?

Lital Keinan Boker has answered Likely

An expert from Haifa University in Epidemiology

That pretty much depends on where and when you refer to.

In the 1980s, when the first randomized clinical trials (RCTs) regarding the efficacy of breast mammograms to save lives were conducted, most did show a reduction in breast cancer mortality of between 25-30%. I believe that these figures still hold in developing countries, where breast cancer is becoming a very common disease, providing that response rates to screening are high enough.

However, current studies from developed countries, many from Scandinavia, do not detect such a reduction anymore; in fact, they show that over-diagnosis of indolent tumors on screening mammography is very likely, while the diagnosis of invasive – and thus more lethal – tumors has not really changed in recent years.

But one should not ignore the circumstances involved. The establishment of national screening programs for breast cancer based on the results of the RCTs from the 1980s in fact lead the way to better awareness to the disease, better accessibility to diagnosis and treatment, better follow up. It often demanded the establishment of special tbreast cancer units that specialized in the diagnosis and treatment of the disease. In other words, following the introduction of screening programs for breast cancer and the establishment of proper standards for them, the medical environmnet significantly changed, for both those who are being screened and those who are not. So it is not surprising that the results (in terms of mortality and survival) nowadays seem to be very similar with and without screening. Put differently, although screening programs for breast cancer in developed countries may not impact mortality directly, the fact that they exist and are closely monitored pave the way to better outcomes independently of screening itself.

 

Do routine mammograms save lives?

Montse Garcia has answered Near Certain

An expert from Catalan Institute of Oncology in Health, Oncology, Epidemiology

Whether breast cancer screening does more harm than good has been debated extensively. The main questions are how large the benefit of screening is in terms of reduced breast cancer mortality and how substantial the harm is in terms of overdiagnosis.

Evidence from randomized trials shows that screening reduces breast cancer mortality by around 20%.  Although advances in adjuvant treatments, a multidisciplinary approach for BC treatment and earlier identification of symptoms by women may have diminished the impact of screening on BC mortality reduction, breast screening extends lives. 

Evidence shows that the number of overdiagnosed cases is non-negligible although there is a lack of agreement on the size of overdiagnosis. The variability on the estimates might be explained by the designs, methods and measurement used. The Independent UK Panel on breast cancer screening stated that although there is no single way to estimate overdiagnosis the two most useful estimates are: from the population perspective, the proportion of all cancers ever diagnosed in women invited to screening that are overdiagnosed and from the perspective of a woman invited to screening, the probability that a cancer diagnosed during the screening period represents overdiagnosis (2). The UK Panel estimated estimated estimated overdiagnosis’ frequency of 11% of breast cancer cases from a population perspective, and about 19% from the perspective of a woman invited to screening (2). 

Although radiation-induced breast cancer is a concern in women who are offered screening. The estimated cumulative risk of death from breast cancer due to radiation from mammographic screening is 1 to 10 per 100,000 women, depending on age and the frequency and duration of screening. It is smaller by a factor of at least 100 than the estimates of death from breast cancer that are prevented by mammographic screening for a wide range of ages (2). [The cumulative radiation exposure associated with a lifetime of mammographic screening (biennal mammogram at ages 50 to 69 years) is equivalent to a single intravenous pielogram or a brain CT.]

After a careful evaluation of the balance between the benefits and adverse effects of mammographic screening, experts from 16 countries met at the International Agency for Research on Cancer (IARC) concluded that there is a net benefit from inviting women 50 to 69 years of age to receive screening (2).  

It seems ethically necessary to inform women about both benefits and risks so that they can actively participate in decision-making and make an informed choice. Information should be made available in a transparent and objective way to women invited to screening so that they can make informed decisions. The need to develop and test decision aids (DAs) for breast cancer screening is clear.   

1.     Marmot MG, Altman DG, Cameron D, Dewar J, Thompson SG, Wilcox M. The benefits and harms of breast cancer screening: an independent review. Br J Cancer. 2013;108:2205–40.

2.     Lauby-Secretan B, Scoccianti C, Loomis D,  Benbrahim-Tallaa L, Bouvard V, Bianchini F, Straif K; International Agency for Research on Cancer Handbook Working Group. Breast cancer screening. Viewpoint of the IARC working group. N Engl J Med. 2015;373:1479

 

Do routine mammograms save lives?

Peter Eby has answered Near Certain

An expert from Virginia Mason Medical Center in Radiology

Mammograms save lives

Research shows that getting a mammogram every year starting at 40, as recommended by the American Congress of Obstetricians and Gynecologists and National Comprehensive Cancer Network, will save the most lives from breast cancer. (1) The Unites States Preventive Services Task Force, American Cancer Society and American College of Radiology all agree on this point. (2)

The largest (3) and longest running (4) randomized breast cancer screening studies in history, re-confirmed that regular mammography cut breast cancer deaths by roughly a third in all women ages 40 and over. Randomized controlled trials underestimate the benefit of screening because not all women who were assigned to receive a mammogram actually did. Therefore, the benefit is actually much greater than presented. Indeed, those of us who detect and treat know that deaths from breast cancer have dropped 35-40% per year since screening mammography became widespread in the United States. (5)

The CISNET models, sponsored in part by the NCI, confirm the real world benefits of mammography. They estimate the mortality benefit of mammography from a low of 25.8% for biennial screening of women 50-74 to a high of 37.8% for annual screening of women 40-74. (1) 

1. Mandelblatt JS, Stout NK, Schechter CB, van den Broek JJ, Miglioretti DL, Krapcho M, et al. Collaborative Modeling of the Benefits and Harms Associated With Different U.S. Breast Cancer Screening Strategies. Ann Intern Med. 2016;164(4):215-225 doi:10.7326/M15-1536 Table 1
2. Oeffinger KC et al. Breast Cancer Screening for Women at Average Risk 2015 Guideline Update From the American Cancer Society JAMA. 2015;314(15):1599-1614.
3. Hellquist BN, Duffy SW, Abdsaleh S, et al. Effectiveness of population-based service screening with mammography for women ages 40 to 49 years: evaluation of the Swedish Mammography Screening in Young Women (SCRY) cohort. Cancer. 2011 Feb 15;117(4):714-22. doi: 10.1002/cncr.25650. Epub 2010 Sep 29.
4. Tabár L, Vitak B, Chen TH, et al. Swedish two-county trial: impact of mammographic screening on breast cancer mortality during 3 decades. Radiology. 2011 Sep;260(3):658-63. doi: 10.1148/radiol.11110469. Epub 2011 Jun 28. PMID: 21712474
5. Noone AM, Howlader N, Krapcho M, et al (eds). SEER Cancer Statistics Review, 1975-2015, National Cancer Institute. Bethesda, MD, https://seer.cancer.gov/csr/1975_2015/, based on November 2017 SEER data submission, posted to the SEER web site, April 2018.

 

Do routine mammograms save lives?

Laszlo Tabar has answered Likely

An expert from Uppsala University in Radiology

It is not the mammograms that save lives, how could they? It is treatment of early breast cancer detected at mammography screening of asymptomatic women” that saves lives. There has not been any other diagnostic or therapeutic method in medicine that has been scrutinized as much as the design, execution and the impact of mammography screening. The answer to the above mentioned statement was clear to every intelligent person already in 1985 – when the seminal trial carried out in Sweden, the so-called Swedish Two-County trial was published. To date, altogether eight randomized controlled trials have also demonstrated the life-saving effect of treatment of screen-detected breast cancers (the Toronto trials were not population-based and partly for that reason and for many other reasons are not peers of the other trials). In addition, numerous population-based service screening studies have confirmed that breast cancer therapy is highly effective against early, screen-detected breast cancers, but has limited efficacy against advanced breast cancers. 

The relative impact of screening versus treatment in any stage cannot be evaluated without knowing the mode of detection in each individual case. Cancer registries do not have this information. I would like to call attention to a comprehensive study including all women in Sweden aged 40-49, in which women in half of the country were invited to mammography screening, while the other half received usual care. This study demonstrated a 29% significant decrease in mortality among women who attended screening regularly (RR 0.71, 95% CI 0.62-0.80). The result was accomplished above and beyond the impact of treatment, as the comparison is contemporaneous, and the stage specific treatment guidelines are uniformly and carefully followed in Sweden independent of detection mode (source). This and other publications from Italy and from the Netherlands provide direct refutation to the belief that advances in adjuvant therapy and chemotherapy, not early detection, are mostly responsible for improved breast cancer prognosis in screened populations in the modern era.

 

Do routine mammograms save lives?

Francis  Boscoe has answered Likely

An expert from University at Albany in Epidemiology, Geography

It is likely that mammograms save at least some lives, but the number saved is almost certainly smaller than the number popularly believed. Our conception of mammography’s benefits is largely influenced by clinical trials conducted in the 1980s and 1990s, when diagnosis of breast cancer at an advanced stage was much more likely to result in death. Today, that is less true. Specifically, the 5-year relative survival for regional stage at diagnosis was 71% in 1985 and 88% in 2009; for distant stage it was 20% in 1985 and 33% in 2009 (data from SEER 9 registries). You haven’t saved a life if the patient was going to be cured later anyway.

More problematically, the rate of late-stage disease has edged upward since the widespread introduction of mammography. The single most important measure of a successful screening program is that the rate of late-stage disease is reduced, as more tumors are being found earlier. The rates of distant stage at diagnosis in 1994, 2004 and 2014 were 7.2, 8.0 and 8.6 (data again from SEER 9). Without passing this test, it is hard to make a strong case for the benefits of mammography.

Nevertheless, I checked “likely”, because the question was whether mammography saves lives, not whether is saves large numbers of lives. It is easy to conduct a thought experiment where we imagine a medically underserved woman who is found via mammogram to have a local lesion, which in the absence of a mammogram would not have been detected until it had grown, spread, become symptomatic, and was no longer treatable. The question is how often does this scenario occur – the data seem to suggest not very often.

Reference: Autier P, Boniol M. Mammography screening: a major issue in medicine. European Journal of Cancer 2018; 90: 34-62. This is an exhaustive review article which cites 280 other papers.

 

Do routine mammograms save lives?

Ritse Mann has answered Near Certain

An expert from Radboud University Medical Center in Oncology, Radiology

The simple answer is: yes, they do. The chance to die from breast cancer is between 15 and 50 percent lower than without mammography screening (depends on model and data used for the estimation, I would say that approximately 30% is realistic).

However, as with all questions that seem straightforward at first, the question is not that easy to answer.

The trouble is that only a few women per thousand women screened are better of, and the rest is paying the price for that (in terms of unnecessary screening examinations, false positive findings, earlier detection of cancers for which the outcome is not changed and over diagnosis/over-treatment of cancers that would never have become apparent during the woman’s life). I guess that the correct question is, is the burden placed upon the female population worth the return? 

I am still inclined to say yes, but this is obviously quite personal, and here counts the fact that I am a man, I am neither burdened with the test nor beneficiary of the test results. The good thing is that women participating might themselves be the ones that profit which makes adoption easier.

All in, it is not that much different from a dentist appointment. Overall this will increase health, and when your teeth are saved you are happy. You just hope that you are not the unlucky person who dies of an unnecessary peridontal infection caused by the dentist that turned into a fatal mediastinitis.

Risks of mammography are not that extreme, but still participating in any form of preventive medicine is not completely without possible harm. That obviously doesn’t mean that you shouldn’t do it.

 

Do routine mammograms save lives?

Angelo Taibi has answered Likely

An expert from University of Ferrara in Biophysics

Breast cancer is the most common cancer in women worldwide and a leading cause of cancer death. Mammography is the main diagnostic tool to achieve early detection of breast cancer so as to implement secondary prevention, i.e. the aim to reduce the impact of a disease that has already occurred.

“Do nothing – Avoid criticism”

 

Do routine mammograms save lives?

Donna  Williams has answered Near Certain

An expert from LSU Health Sciences Center New Orleans in Health, Oncology

Yes, in many cases mammograms are known to detect breast cancer masses when they are very small, much smaller than one would detect just by feeling. By detecting these masses when they are small, they can be removed and treated before they spread cancerous cell to other parts of the body. That being said, it is important to note what mammography will and will not do. Mammography will detect masses, but it will not tell us how these masses are likely to behave in the body. A certain percentage of masses that are removed and treated would be expected to be “clinically insignificant,” that is if mammography had never been performed, the mass never would have progressed and likely the woman would never have even known it was there. But at this stage of the game, we are unable to tell those that would progress from those that wouldn’t. On the flip side, some cancers are very aggressive. While mammography is recommended every two years, there are certain types of cancers, though rare, that were occur between mammograms, known as “interval” cancers. All this to say that mammography is a tool, but an imperfect one.

 

Do routine mammograms save lives?

Alison  Dunning  has answered Near Certain

An expert from University of Cambridge in Genomics

The NHS has implemented an evidence-based, national mammographic screening programme for all U.K. women aged between 50 and 70. Women in that age group are invited for 7 mammograms over the 20 year period. The evidence underpinning the screening program is set out here: https://cks.nice.org.uk/breast-screening#!scenario. The calculated aim is to save one life for every 180 women attending screening. New data may lead to a revision of this calculation, but it is the best currently available.

 

Do routine mammograms save lives?

Hanaa AlKhawari has answered Likely

An expert from Ministry of Health, Kuwait in Radiology

It picks up cancer at an early stage hence the survival rate is higher.

 

Do routine mammograms save lives?

Paul Carson has answered Near Certain

An expert from University of Michigan in Biomedical Engineering, Radiology, Physics

“…since mammography became widespread in the 1980s, the U.S. breast cancer death rate in women, unchanged for the previous 50 years, has dropped 43 percent. Breast cancer deaths in men, who have the same treatment as women but are not screened, have not declined .”

 [MOU1] https://www.acr.org/Media-Center/ACR-News-Releases/2018/New-ACR-and-SBI-Breast-Cancer-Screening-Guidelines-Call-for-Significant-Changes-to-Screening-Process?utm_source=040718-AIA&utm_medium=Email&utm_campaign=AdvocacyNews1&_zs=idcUD1&_zl=nswO4

https://www.acr.org/Media-Center/ACR-News-Releases/2018/New-ACR-and-SBI-Breast-Cancer-Screening-Guidelines-Call-for-Significant-Changes-to-Screening-Process?utm_source=040718-AIA&utm_medium=Email&utm_campaign=AdvocacyNews1&_zs=idcUD1&_zl=nswO4

 

Do routine mammograms save lives?

Katherine Crew has answered Likely

An expert from Columbia University in Internal Medicine, Oncology

Data from several randomized controlled trials of screening mammography have demonstrated a 20-25% relative risk reduction in breast cancer-specific mortality. However, these trials had some design flaws and are now outdated given current improvements in breast imaging (i.e., digital mammography, tomosynthesis), as well as advancements in the treatments for early-stage breast cancer which may diminish the benefits of mammography screening for early detection.

In addition, the number needed to screen in order to prevent one breast cancer-related death may be relatively high (particularly among women less than 50 years of age). As a result, the benefits of screening for lowering breast cancer mortality need to be carefully weighed against the potential harms of false positive results (unnecessary breast biopsies) and over-diagnosis, not to mention the costs of screening on our healthcare system.

Perhaps the best approach is to conduct risk-stratified screening, where high-risk women (i.e., strong family history of breast cancer) should undergo more frequent screening and supplemental screening to improve the early detection of breast cancer, whereas low-average risk women can undergo routine mammography every 2 years at age 50-74 (according to USPSTF guidelines). This may lead to a better allocation of resources and help to maximize the benefits and minimize the harms of mammography screening.

 

Do routine mammograms save lives?

Alexander Wong has answered Near Certain

An expert from University of Waterloo in Biomedical Engineering

There is substantial evidence over the years of trials that mammography screenings reduce breast cancer mortality, especially for women aged 40 years and over, so whether it saves lives is without question. However, the significant overdiagnosis associated with mammograms is indeed a problem and can have profound negative effects on those who are treated unnecessarily, and so whether to undergo routine mammograms, especially for younger women who are also at lower risk of breast cancer, needs to be assessed on an individual basis.

 

Do routine mammograms save lives?

Laura Mazilu has answered Likely

An expert from Ovidius University in Oncology

Answer is likely, early detection generally saves lives, but…

Screening mammography recommendations are all in average risk women and decisions should be individualised!

There are still questions regarding – ages to begin and end routine screening, screening intervals, benefits of screening and potential harms, appropriate use of various modalities (old-fashion modalities vs new imaging techniques), Issues that vary depending on an individual’s risk for breast cancer. 

 

Do routine mammograms save lives?

Anne Marie McCarthy has answered Near Certain

An expert from Massachusetts General Hospital in Epidemiology

Routine mammography screening reduces breast cancer mortality by approximately 25%. Nelson, Heidi D., et al. “Effectiveness of breast cancer screening: systematic review and meta-analysis to update the 2009 US Preventive Services Task Force recommendation.” Annals of internal medicine 164.4 (2016): 244-255. 

However, this 25% estimate is based on old clinical trials data, and so the magnitude of the benefit of mammography screening today is a bit uncertain.  However, statistical modeling studies suggest that both mammography screening and treatment explain the reductions in breast cancer mortality seen over the past few decades.  https://cisnet.cancer.gov/breast/landmark.html

It is important to note that like all screening tests, mammography screening is not perfect – the false-positive rate is significant and some breast cancers will be missed.  Therefore the tradeoff of risks and benefits of mammography screening is an important consideration. 

There are many open questions about how best to implement ‘routine’ mammography screening, in terms of age to start and stop screening, and how often to get screened. Current research is focusing on better identifying risk factors for breast cancer to enable better targeting of mammography screening to women at highest risk for dying of breast cancer.

 

Do routine mammograms save lives?

Bethany Niell has answered Near Certain

An expert from H. Lee Moffitt Cancer Center and Research Institute in Radiology

Pooled data from randomized controlled trials (RCTs) demonstrate that screening mammograms decrease breast cancer deaths by 20-40%. However, not all women enrolled in trials will participate in the trial as intended, so RCTs underestimate the potential benefit of screening.

What about screening mammograms performed in women outside of scientific trials or studies?

Women who actually underwent screening mammography in large population-based screening programs in Europe and Canada did benefit from screening. Screening reduced breast cancer mortality by 38-40%.

 

Do routine mammograms save lives?

Stamatia Destounis has answered Near Certain

An expert from Elizabeth Wende Breast Care in Radiology

Since 1990, when use of mammography screening became widespread, breast cancer mortality has decreased by 39% [1]. Prior to this, the mortality rate was unchanged for the previous 50 years. This trend continues currently, as death rates due to breast cancer have, on average, fallen 1.8% each year from 2005-2015 [2]. Mortality reduction from the disease has been proven to be due to screening mammography through multiple Randomized Controlled Trials (RCTs) and observational studies, including the Two County Trial in Sweden, which found through 29-year-follow-up, a 30% mortality reduction [3]. Studies such as this prove that mammography screening is directly associated with reductions in mortality, and that the mortality benefit from screening continues over time. Annual screening beginning at age 40 has been proven to also increase life years gained; 189, compared to later and less frequent screening (149 LYG with annual 45-54, biennial 55-79; 110 LYG biennial 50-74) [4]. The performance of annual mammography promotes early detection; it allows us to find and then treat breast cancer at an early stage, when treatment is more effective, less harmful and less expensive. Each missed year of mammography screening has been shown to be associated with a decline in overall survival; 2.3-fold increased change, compared with those undergoing yearly mammography [5].

Though treatment for breast cancer has also improved greatly over the years, it is still most effective and least harmful for the patient when cancers are found early. The 5-year survival rate for localized female breast cancer is 99%; for cancers which have spread to regional lymph nodes, this rate drops to 85%, and for those diagnosed with very advanced stage cancers that have spread to distant areas of the body, the rate drops significantly to 26% [6]. Studies in which all women have had access to modern therapies have shown that women who participate in screening have a markedly lower death rate from breast cancer than those who do not participate despite the fact that all have access to the same therapies [7].

National societies, such as the American College of Radiology and the Society of Breast Imaging, recommend screening mammography beginning at age 40, and continuing annually. Attending screening mammography annually allows for the maximum benefits to be observed; early detection of nonpalpable cancers, when they are smaller size, earlier stage, and more likely to be curable, ultimately reducing breast cancer deaths, requiring less extensive treatment, and decreasing the occurrence of advanced disease at diagnosis. “Virtually every responsible group agrees that the science shows that mammographic screening saves lives.”- Kopans [8]

References

1.     DeSantis CE, MA J, Goding Sauer A, Newman LA, Jemal A. Breast cancer statistics, 2017, racial disparity in mortality by state. CA: A Cancer Journal for Clinicians, 67: 439-448. 
2.     Siegel RL, Miller KD, Jemal A. Cancer statistics, 2018. CA: A Cancer Journal for Clinicians, 68: 7-30.
3.     Tabar L, Vitak B, Chen TH, et al. Swedish Two-County Trial: Impact of Mammographic Screening on Breast Cancer Mortality during 3 Decades. Radiology 2011; 260(3): 658-663.
4.     Arleo EK, et al. Comparison of Recommendations for Screening Mammography Using CISNET Models. Cancer 2017; 123:3673-80.
5.     Engel JM, Stankowski-Drengler TJ, Stankowski RV, et al. All-cause mortality is decreased in women undergoing annual mammography before breast cancer diagnosis. AJR 2015; 204(4): 898-902.
6.     American Cancer Society. Breast Cancer Facts & Figures 2015-2016. Atlanta: American Cancer Society, Inc. 2015.
7.     Kopans D. An open letter to panels that are deciding guidelines for breast cancer screening. Breast Cancer Res Treat 2015; doi 10.1007/s10549-015-3373-8
8.     Kopans D. Point: The New England Journal of Medicine Article Suggesting Overdiagnosis From Mammography Screening Is Scientifically Incorrect and Should Be Withdrawn. JACR 2013; doi:10.1016/j.jacr.2013.01.024 

 

Do routine mammograms save lives?

Stephen Feig has answered Near Certain

An expert from University of California, Irvine School of Medicine in Radiology, Epidemiology, Internal Medicine

As an expert on screening mammography controversies, I’d be happy to share my recommendation for annual screening starting at age 40 years because it will result in a 50% reduction in breast cancer deaths.

Randomized clinical trials such as the Swedish Two-County Trial conducted in the 1980’s proved that screening reduced breast cancer mortality by 35%. Results from more recent studies have shown even greater reductions of over 50% in death rates because of advances in mammography equipment such as digital mammography and digital tomosynthesis and more realistic methods of benefit calculations.

  Here is other refutation of errors/mistakes in the anti-screening rhetoric of the Cochrane Collaboration and the US Preventive Services Task Force.

Proper estimation of the rate of over-diagnosis from screening is no more than 0%-3%. This hypothetical risk is slight compared with the proven benefit from screening.

   The “false positives” from screening are mostly having to return for additional mammographic images or breast ultrasound or rarely for a minimally invasive breast biopsy. This  additional workup is acceptable to most women. The  anxiety from this workup is relatively slight compared to the anxiety from developing late stage breast cancer .

  The hypothetical risk from the low radiation  from mammography today is negligible or non-existent compared to the proven benefits from screening according to all reputable research studies verified by the National Council on Radiation Protection and Measurements (NCRP) in the United States.

The best approach to reduce breast cancer deaths is detection at  the earliest possible stage using mammography along with supplementary ultrasound and breast MRI as needed. Smaller cancers respond much better to treatment than do larger cancers. 

Newer treatments do not substitute for high quality screening. Together, they offer women the best chance of survival !

 

Do routine mammograms save lives?

Su-Ju Lee has answered Near Certain

An expert from University of Cincinnati in Radiology

Multiple studies had shown that routine screening mammogram reduces breast cancer death rate by 30-44%. The benefit is derived from early cancer detection that allows more effective treatment. Early detection with mammography also reduces the severity of treatment that women with breast cancer must go through.

The most breast cancer deaths are prevented and lives saved when screening mammography is performed annually beginning at age 40. In our clinic, breast cancers are diagnosed in women in their 40’s frequently. In fact, due to the longer life expectancy of younger women, 40% of all the years of life saved by mammography are among women in their 40’s.

The primary limitations of screening mammography are that it will not find all cancers and may require some additional testing for non-cancer. The technological advancement in 3-D mammogram (digital breast tomosynthesis) has been shown to improve cancer detection and decrease screening recall by eliminating the issue of tissue overlap with standard 2-D digital mammogram.

I am sure that being called back for additional testing or breast biopsy causes anxiety, but studies showed that most women do not see this transient anxiety as serious road block for them to undergo future mammography screening. Compared to the life-saving benefit of screening mammography, the “harm’ of anxiety seems overly exaggerated.

 

Do routine mammograms save lives?

Yilin  Yoshida has answered Likely

An expert from Univeristy of Missouri-Columbia in Epidemiology, Behavioural Science

Our recent study (1), authored by Dr. Eduardo J. Simoes, Dr. Chester L. Schmaltz, Jeannette Jackson-Thompson and me showed that mammography rate decreased from 2003 (83.5%) to 2011 (80.1%) in the state of Missouri. Recent controversies surrounding appropriate age groups for recommending mammography may have contributed to this decline (2-7). The debate about the benefits and harms of mammography screening is not unique to the U.S., however, it certainly causes confusion to the public and may have discouraged women from using the screening. Dr. Eduardo J. Simoes and I summarized breast cancer screening guidelines for women with average risk from different recommending bodies as below.

U.S. Preventive Services Task Force 2016 (6)

Women aged 50-74 should have mammography biennially. Women in their 40s should have an option of getting a mammogram after discussing the risks and benefits with physician.

American Academy of Family Physicians 2016 (2)

Mirror U.S. Preventive Services Task Force guidelines.

American Cancer society 2015 (5)

Women ≥45 years should have mammography annually. Women should be able to start the annual screening as early as age 40.

American College of Obstetricians and Gynecologists 2017 (8)

Women ≥40 years should have mammography annually or biennially based on an informed, shared decision-making process that includes a discussion of the benefits and harms of screening.

American College of Radiology 2018 (4)

Women ≥40 years should have mammography annually.

American Society of Breast Imaging (3)

Mirror American College of Radiology guidelines.

American College of Physicians (7)

Clinicians should encourage biennial mammography screening in women aged 50 to 74. Women in their 40s should have an option of biennial mammography screening if they are informed the benefits and harms and request it.

Mammography’s impact on breast cancer mortality has almost reached consensus in many western countries. Three high quality meta-analyses of randomized control trials all showed around 20% mortality reduction associated with the screening (UK Independent Panel: relative risk [RR], 0.80 [95% CI, 0.73-0.89]; Canadian Task Force: RR, 0.82 [95% CI, 0.74-0.94]; Nordic Cochrane Centre: RR, 0.81 [95% CI, 0.74-0.87]) (9-11). However, uncertainties remain about the magnitude of the associated reduction in the entire U.S. population, among women younger than 50 years old, and with annual screening compared with biennial screening (12). Overall, evidence on mammography’s mortality reduction is strong, however, estimates of the reduction associated with varying age to start and stop the screening, and screening frequency still need to be clarified (12).

Much of current debate related to harm of mammography is over-diagnosis and over-treatment. Over-diagnosis occurs when a mammogram detects ductal carcinoma in situ (DCIS), also called stage 0 or pre-invasive breast carcinoma, or small, slowing-growing invasive breast cancers that would have never caused symptoms or problems if left untreated (13). For now, women diagnosed with DCIS are treated with lumpectomy plus radiation therapy or mastectomy, and possibly hormone therapy and/or chemotherapy (13). Because not all cases will progress, some women may be over-treated. One key solution for over-diagnosis and over-treatment is to know which cases of DCIS will become invasive breast cancer. Unfortunately, the natural history of DCIS is still not well understood and modifiable risk factors associated with DCIS have not been fully identified. Previous studies suggested that many risk factors, such as age at first term pregnancy, older menopause and family history for DCIS are also risk factors for invasive breast cancer, indicating similar etiologic pathways ?(14,15). However, studies evaluating DCIS are limited by small samples sizes, mixed populations of screened and unscreened cases and controls, inclusion of patients with lobular carcinoma in situ, and lack of central pathology review to avoid disease misclassification (16). Future research should gain a deeper understanding of the molecular mechanisms of invasion that could lead to new therapeutic strategies to treat DCIS, or prevent it from developing and elucidating clinical behavior and factors related to progression of the DCIS (e.g., hormonal exposure and obesity). To achieve this, a concerted effort among patients with DCIS, clinicians, and basic and population scientists are needed.

Finding a balance between benefits and harms of mammography is difficult in view of the uncertainties of published results. On the positive side, mammography confers mortality reduction benefit due to early detection and treatment. On the negative side, women may face chance of being over-diagnosed and over-treated, though estimates are highly heterogeneous and very depending on the analytic approach (e.g., over-diagnosis rate was 11% to 22% from RCTs). Clear communication of these harms and benefits to women are important. Easy to understand and coherent approaches of presenting statistical information should be introduced and encouraged (17).   

1.           Yoshida Y, Schmaltz CL, Jackson-Thompson J, Simoes EJ. The impact of screening on cancer incidence and mortality in Missouri, USA, 2004-2013. Public Health. 2018;154:51-58.
2.           American Academy of Family Physicians. USPSTF, AAFP Issue Final Breast Cancer Screening Recommendations. In:2016.
3.           American College of Radiology. New ACR and SBI Breast Cancer Screening Guidelines Call for Significant Changes to Screening Process. In:2018.
4.           Monticciolo DL, Newell MS, Moy L, Niell B, Monsees B, Sickles EA. Breast Cancer Screening in Women at Higher-Than-Average Risk: Recommendations From the ACR. J Am Coll Radiol. 2018;15(3 Pt A):408-414.
5.           Oeffinger KC, Fontham ET, Etzioni R, et al. Breast Cancer Screening for Women at Average Risk: 2015 Guideline Update From the American Cancer Society. Jama. 2015;314(15):1599-1614.
6.           Siu AL, Force USPST. Screening for Breast Cancer: U.S. Preventive Services Task Force Recommendation Statement. Annals of internal medicine. 2016;164(4):279-296.
7.           Wilt TJ, Harris RP, Qaseem A, High Value Care Task Force of the American College of P. Screening for cancer: advice for high-value care from the American College of Physicians. Annals of internal medicine. 2015;162(10):718-725.
8.           Committee on Practice Bulletins—Gynecology. Breast Cancer Risk Assessment and Screening in Average-Risk Women. The American College of Obstetricians and Gynecologists2018.
9.           Gotzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev. 2011(1):CD001877.
10.         Independent UKPoBCS. The benefits and harms of breast cancer screening: an independent review. Lancet. 2012;380(9855):1778-1786.
11.         Tonelli M, Connor Gorber S, Joffres M, et al. Recommendations on screening for breast cancer in average-risk women aged 40-74 years. Cmaj. 2011;183(17):1991-2001.
12.         Myers ER, Moorman P, Gierisch JM, et al. Benefits and Harms of Breast Cancer Screening: A Systematic Review. Jama. 2015;314(15):1615-1634.
13.         Weighing the benefits and risks of mammography. https://ww5.komen.org/BreastCancer/TheMammographyDebate.html. Accessed May. 2018.
14.         Claus EB, Stowe M, Carter D. Breast carcinoma in situ: risk factors and screening patterns. Journal of the National Cancer Institute. 2001;93(23):1811-1817.
15.         Zeleniuch-Jacquotte A, Gu Y, Shore RE, et al. Postmenopausal levels of sex hormones and risk of breast carcinoma in situ: results of a prospective study. International journal of cancer. 2005;114(2):323-327.
16.         Kuerer HM, Albarracin CT, Yang WT, et al. Ductal carcinoma in situ: state of the science and roadmap to advance the field. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2009;27(2):279-288.
17.         Barrett B, McKenna P. Communicating benefits and risks of screening for prostate, colon, and breast cancer. Fam Med. 2011;43(4):248-253.

 

Do routine mammograms save lives?

Pragya Dang has answered Near Certain

An expert from Brigham and Women’s Hospital in Radiology

Yes, Mammograms save lives

Decades of research has shown that getting a yearly mammogram starting at age 40, saves most lives.  Breast cancer deaths have decreased by 39% since screening mammography became widespread in the 1990s. Multiple Randomized Controlled Trials (RCT) have shown mortality reduction from breast cancer by a third from screening mammography in all women ages 40 and above. These RCTs in fact underestimate the benefit of screening since not all women assigned to receive a mammograms actually did. Therefore, the actual benefit from screening is even greater than presented.  

Large population-based screening programs in Europe and Canada have shown that breast cancer mortality was reduced by 38-40% in women who actually underwent screening mammography,

Annual screening mammography starting at age 40 as recommended by national organizations such as American College of Radiology and the Society of Breast Imaging saves most lives from breast cancer. It also has other benefits such as detection of smaller nonpalpable cancers at an earlier stage when they are curable and require less aggressive treatment. 

 

Do routine mammograms save lives?

Kelly Biggs has answered Near Certain

An expert from  Tyrone Hospital in Radiology

Mammography is among the most exhaustively studied medical procedures, with research dating from the 1960s to present. Meta-analyses of randomized controlled trials (RCTs) clearly demonstrate a reduction in breast cancer deaths for women who undergo screening mammograms compared to those who do not. (1) These early studies show the reduction in mortality to be about 20 percent.

Relatively recent observational studies demonstrate an even more substantial benefit. The RCTs were bound by limitations of older technology and restrictions of study design. For example, the older studies assessed protection for women invited to screen and not for women who actually participated in screening. The Pan-Canadian Study of Mammography Screening published in 2014 showed a reduction in breast cancer death of about 40 percent. This study included about 2.8 million women. (2)  

The American College of Radiology, the US Preventive Services Task Force, and the American Cancer Society currently have separate recommendations for when to begin screening, and how often to have screening mammograms. Differences are based on detection rates between certain age groups balanced against issues such as patient anxiety and number of medical procedures performed. (3). It is important for women and clinicians to understand that, despite these differences, these three institutions all agree that mammograms save lives. Moreover, the data used by each of these groups confirm the most lives are saved when screening is performed annually beginning at age 40. (3)

References:

1. Tabár L, Yen AM-F, Wu WY-Y, Chen SL-S, Chiu SY-H, Fann JC-Y, et al. Insights from the Breast Cancer Screening Trials: How Screening Affects the Natural History of Breast Cancer and Implications for Evaluating Service Screening Programs. The Breast Journal. 2014;21(1):13-20.
2. Coldman A, Phillips N, Wilson C, Decker K, Chiarelli AM, Brisson J, et al. Pan-Canadian Study of Mammography Screening and Mortality from Breast Cancer. JNCI Journal of the National Cancer Institute. 2014;106(11):dju261-dju.
3. Monticciolo D, Newell M, Hendrick R, Helvie M, et al. Breast Cancer Screening for Average-Risk Women: Recommendations From the ACR Commission on Breast Imaging. J Am Coll Radiol 2017; 14: 1137-1143

 

Do routine mammograms save lives?

Robert Kaplan has answered Unlikely

An expert from Stanford University in Health, Behavioural Science

This is a matter of some controversy. I do not believe that mammography save lives. Numerous studies do suggest that breast cancer screening increases the rate of cancer detection. However, in trials that randomly assigned women to be screened or not screened, there are only minor differences in deaths from breast cancer and those are limited to women between the ages of 50 and 70 years. The larger controversy concerns death from any cause. Averaged across all high quality studies, women randomly assigned to mammography do not live longer than those assigned to usual care.

Do routine mammograms save lives?

Ian  Bennett has answered Near Certain

An expert from Independent in Oncology, Endocrinology

Both diagnostic and screening mammography undoubtedly saves lives, and the introduction of population-based mammography screening programmes for women over the age of 50 years in particular has been the major factor contributing to the observed reduction in mortality from breast cancer over the past 15 years.The evidence for the survival benefits associated with screening mammography have been clearly shown in multiple national and international trials over the past 40 years, and on the whole these studies have demonstrated a 30% reduction in mortality amongst women participating in mammography screening.

Earlier detection of breast cancers is not only associated with improved prognosis, but also enables many women to be able to avoid more severe treatments such as mastectomies and chemotherapy.