Do blood tests find cancer
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Can Blood Tests Detect Cancer?
Introduction to Blood Tests for Cancer Detection
Blood tests have emerged as a promising tool for the early detection of cancer. These tests aim to identify cancer-specific biomarkers, such as circulating tumor DNA (ctDNA) and protein markers, in the blood. Early detection is crucial as it significantly improves the chances of successful treatment and survival.
Multi-Analyte Blood Tests: CancerSEEK
One of the notable advancements in this field is the development of CancerSEEK, a multi-analyte blood test designed to detect eight common types of cancer. This test evaluates eight circulating protein biomarkers and tumor-specific mutations in circulating DNA. In a study involving 1,005 patients with non-metastatic cancers and 850 healthy controls, CancerSEEK demonstrated a sensitivity range of 69% to 98% depending on the cancer type, and a specificity of over 99%. This high specificity means that the test has a low rate of false positives, making it a reliable tool for early cancer detection.
Combining Blood Tests with Imaging: PET-CT
Another approach to enhancing the accuracy of blood tests for cancer detection is combining them with imaging techniques like positron emission tomography-computed tomography (PET-CT). In a study involving 10,006 women with no prior history of cancer, a multicancer blood test followed by PET-CT imaging detected 26 cancers, 60% of which were surgically removed with curative intent. This combination not only improved the detection rates but also minimized unnecessary follow-up procedures, demonstrating the feasibility and safety of integrating blood tests into routine clinical care.
Accuracy of Tumor Origin Detection
Determining the tissue of origin (TOO) is critical for guiding appropriate treatment. Blood-based multi-cancer early detection (MCED) tests have shown promising results in this regard. A systematic review and meta-analysis revealed that these tests could accurately identify the primary site of cancer in 79% of cases. The accuracy varied across cancer types, with colorectal cancers showing the highest accuracy and liver & bile duct cancers the lowest . This capability is essential for tailoring treatment plans to the specific type of cancer detected.
Specific Blood Tests for Colorectal Cancer
For colorectal cancer, fecal occult blood tests (FOBT) have been widely used. Immunochemical FOBTs (I-FOBT) have shown better performance compared to guaiac-based FOBTs (G-FOBT). In a randomized study, I-FOBTs had higher participation and detection rates for advanced adenomas and cancer, making them a more effective screening tool . Additionally, full blood count (FBC) tests have been explored for colorectal cancer detection, with certain components like red blood cells and hemoglobin showing associations with cancer diagnosis.
Large-Scale Trials and Future Directions
Large-scale trials like the NHS-Galleri are underway to assess the effectiveness of blood tests in reducing late-stage cancer incidence. This trial involves over 140,000 participants and aims to determine whether a multi-cancer early detection test can be integrated into population screening programs. The Early Cancer Detection Consortium is also working on identifying and validating blood-based biomarkers for early cancer detection, further expanding the potential of these tests.
Conclusion
Blood tests have shown significant potential in detecting various types of cancer at an early stage. Multi-analyte tests like CancerSEEK, when combined with imaging techniques, offer high sensitivity and specificity. The ability to accurately determine the tissue of origin further enhances their clinical utility. As research progresses and large-scale trials provide more data, blood tests could become a standard tool in cancer screening and early detection, ultimately improving patient outcomes.
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