Cancer screening blood test
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Advances in Cancer Screening Blood Tests
Introduction to Cancer Screening Blood Tests
Cancer screening blood tests have emerged as a promising tool for early detection of various cancers. These tests aim to identify molecular markers in the blood that indicate the presence of cancer, potentially allowing for earlier and more effective treatment. This article synthesizes recent research on the feasibility, accuracy, and clinical utility of these tests.
Feasibility and Safety of Multicancer Blood Tests
Recent studies have demonstrated the feasibility and safety of incorporating multicancer blood tests into routine clinical care. A large-scale study involving 10,006 women aged 65 to 75 years without a prior history of cancer showed that a blood test detecting DNA mutations and protein biomarkers could identify 26 cancers of different types. When combined with positron emission tomography-computed tomography (PET-CT), the specificity and positive predictive value (PPV) of the blood test increased significantly, leading to surgical removal of nine cancers with curative intent .
Colorectal Cancer Screening: Faecal Occult Blood Tests
Colorectal cancer (CRC) screening has traditionally relied on faecal occult blood tests (FOBTs). A systematic review of randomized controlled trials found that screening with guaiac-based FOBTs (G-FOBT) and immunochemical FOBTs (I-FOBT) reduced CRC mortality by 16% . However, I-FOBTs demonstrated higher participation and detection rates for advanced adenomas and cancer compared to G-FOBTs, suggesting that I-FOBTs may be more effective for CRC screening Van Rossum2008Hol2009.
Accuracy of Tumor Origin Detection in Blood-Based Tests
The accuracy of determining the tumor origin is crucial for guiding appropriate treatment. A meta-analysis of cell-free DNA (cfDNA)-based multicancer early detection (MCED) tests showed that these tests could accurately predict the tissue of origin in 79% of cases. The accuracy varied across cancer types, with colorectal cancers having the highest accuracy and liver & bile duct cancers the lowest .
Large-Scale Trials and Population Screening
The NHS-Galleri trial is a significant ongoing study designed to assess whether a blood-based MCED test can reduce late-stage cancer incidence. This trial has enrolled over 140,000 participants from the general population of England, aged 50-77 years. Participants with a detected cancer signal are referred for further diagnostic testing, while the trial aims to demonstrate a reduction in stage III and IV cancer diagnoses .
Promising Biomarkers for Early Detection
Research has identified several promising blood-based biomarkers for early cancer detection. A systematic review highlighted the anti-p53 antibody as a particularly promising marker for colorectal cancer, with consistent findings across multiple studies. Other potential biomarkers include proteins such as carcinoembryonic antigen (CEA) and C-reactive protein (CRP), as well as various metabolites and DNA methylation patterns Harlid2021Hundt2007.
Conclusion
Cancer screening blood tests represent a significant advancement in early cancer detection. Studies have shown their feasibility, safety, and potential to improve early diagnosis and treatment outcomes. While further research is needed to validate these findings and optimize the tests, the integration of blood-based screening into routine clinical care holds promise for reducing cancer mortality and improving patient outcomes.
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