Is breast cancer more likely to progress during pregnancy?
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Breast Cancer Progression During Pregnancy: An Analysis
Introduction to Breast Cancer and Pregnancy
Breast cancer during pregnancy, also known as pregnancy-associated breast cancer (PABC), is a rare but increasingly observed condition due to the trend of delayed childbearing. This article synthesizes current research to address whether breast cancer is more likely to progress during pregnancy.
Increased Risk of Breast Cancer Post-Pregnancy
Several studies indicate a transient increase in the risk of breast cancer following childbirth. A comprehensive case-control study in Sweden found that uniparous women (those with one child) had a higher risk of developing breast cancer for up to 15 years post-childbirth compared to nulliparous women (those with no children)1. This risk was particularly pronounced in women who had their first child at an older age. However, the risk decreased in the long term, suggesting a dual effect of pregnancy on breast cancer risk1.
Aggressiveness and Prognosis of Breast Cancer During Pregnancy
Breast cancer diagnosed during pregnancy is often more aggressive and is frequently characterized by a triple-negative phenotype, which is associated with poorer prognosis and outcomes2. A meta-analysis of 41 studies revealed that women diagnosed with breast cancer during pregnancy or up to five years postpartum had a significantly higher risk of death and disease progression compared to non-pregnant controls3. This increased risk was most notable in those diagnosed postpartum3.
Obstetric and Perinatal Complications
Women diagnosed with breast cancer during pregnancy face higher risks of obstetric and perinatal complications. A population-based study in Sweden reported increased risks of preterm birth, low birth weight, and other related adverse outcomes in these women4. These risks were particularly elevated when the cancer was diagnosed in the second trimester4.
Mechanisms Behind Poor Prognosis
The poor prognosis of PABC may be attributed to the mammary microenvironment during and after pregnancy. The remodelling of the mammary gland to its pre-pregnant state involves pro-inflammatory and wound-healing mechanisms that may promote tumor-cell dissemination5. This hypothesis suggests that the physiological changes during pregnancy create a tumor-promoting environment.
Short-Term Increase in Risk
Data from hospital-based case-control studies in Italy support the notion of a short-term increase in breast cancer risk following full-term pregnancy. Women who had given birth within three years prior had a significantly higher relative risk of breast cancer compared to those whose last birth was ten or more years before6. This transient increase in risk is thought to contrast with the long-term protective effects of early childbirth.
Immune Microenvironment and Risk Profiles
The tumor immune microenvironment in PABC differs from that in early-onset breast cancer in non-pregnant women. PABC is characterized by specific patterns of tumor-infiltrating lymphocytes (TILs) and immune markers, which are associated with higher risks of relapse and disease-related death7. This unique immune landscape underscores the need for tailored therapeutic approaches.
Conclusion
In summary, breast cancer diagnosed during pregnancy is associated with a higher risk of progression and poorer prognosis. The transient increase in risk post-childbirth, the aggressive nature of PABC, and the unique tumor microenvironment all contribute to this heightened risk. Understanding these factors is crucial for developing effective management strategies for pregnant women with breast cancer.
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Most relevant research papers on this topic
Transient increase in the risk of breast cancer after giving birth.
Pregnancy increases the risk of breast cancer transiently after giving birth but reduces it in later years, with a greater reduction in risk in women with two pregnancies.
Observational Study
Highly CitedBreast Cancer During Pregnancy: A Marked Propensity to Triple-Negative Phenotype
Breast cancer during pregnancy is often triple negative, with poorer prognosis and outcomes, but targeted gene therapies may help manage this aggressive disease.
The prognosis of women diagnosed with breast cancer before, during and after pregnancy: a meta-analysis
Pregnancy before or during breast cancer diagnosis increases death risk, while pregnancy after diagnosis reduces death risk.
Meta-Analysis
Rigorous JournalHighly CitedRisk of obstetric and perinatal complications in women presenting with breast cancer during pregnancy and the first year postpartum in Sweden 1973–2017: A population‐based matched study
Breast cancer during pregnancy is associated with higher risks of preterm birth and low birthweight, but not other maternal pregnancy complications or adverse outcomes in children.
Observational StudyPregnancy-associated breast cancer and metastasis
Pregnancy-associated breast cancer may have a poor prognosis due to the mammary microenvironment becoming tumor-promoting due to pre-pregnant mammary gland remodelling and pro-inflammatory mechanisms.
Highly CitedShort term increase in risk of breast cancer after full term pregnancy.
A full term birth leads to a short-term increase in the risk of breast cancer, which can overcome the long-term protection of early pregnancy at an early age.
Meta-AnalysisHighly CitedBreast cancer in pregnancy and lactation.
Pregnancy does not directly contribute to the development or accelerated progression of breast cancer, but may delay diagnosis due to physiological changes in the breast.
Breast Cancer during Pregnancy as a Special Type of Early-Onset Breast Cancer: Analysis of the Tumor Immune Microenvironment and Risk Profiles
Breast cancer during pregnancy (PrBC) has a distinct tumor microenvironment with specific immune subpopulations, a higher risk of relapse and disease-related death, and routine assessment of TILs may help identify clinically relevant subsets.
Observational StudyPrognosis of pregnancy-associated breast cancer: a meta-analysis of 30 studies.
Pregnancy-associated breast cancer (PABC) is associated with poor survival and higher relapse risk, particularly in those diagnosed shortly post-partum.
Meta-AnalysisHighly CitedPregnancy After Breast Cancer: A Systematic Review and Meta-Analysis
Pregnancy after breast cancer is safe and may improve disease-free and overall survival rates, making it a crucial component of survivorship care plans.
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