Blood test that detects cancer
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Blood Tests for Early Cancer Detection
Introduction to Blood-Based Cancer Detection
Early detection of cancer significantly improves treatment outcomes and survival rates. Traditional screening methods, such as mammography and colonoscopy, are effective but often limited to specific cancer types and can be invasive. Recent advancements in blood-based tests offer a promising alternative for early cancer detection, providing a non-invasive, comprehensive approach to identifying multiple cancer types.
Multi-Analyte Blood Tests: CancerSEEK
Overview of CancerSEEK
CancerSEEK is a pioneering blood test that detects eight common cancer types by analyzing circulating protein biomarkers and tumor-specific mutations in cell-free DNA (cfDNA). In a study involving 1,005 patients with non-metastatic cancers and 850 healthy controls, CancerSEEK demonstrated a sensitivity range of 69% to 98% and a specificity of over 99%. This high specificity means that false positives are rare, making CancerSEEK a reliable tool for early cancer detection.
Cancer Types Detected
CancerSEEK is capable of detecting cancers of the ovary, liver, stomach, pancreas, esophagus, colorectum, lung, and breast. Notably, it shows high sensitivity for cancers that currently lack effective screening methods, such as ovarian and pancreatic cancers.
Combining Blood Tests with Imaging: PET-CT Integration
Feasibility Study
A large-scale feasibility study evaluated the integration of a multicancer blood test with positron emission tomography-computed tomography (PET-CT) imaging. This study involved 10,006 women with no prior history of cancer. The blood test detected 26 cancers, and PET-CT imaging confirmed and localized these cancers, leading to surgical removal in nine cases. This approach demonstrated that combining blood tests with imaging could enhance early detection and reduce unnecessary follow-up procedures.
Safety and Efficacy
The study highlighted the safety of this combined approach, with only 0.22% of participants undergoing unnecessary invasive procedures due to false positives. The specificity and positive predictive value (PPV) of the blood test alone were 98.9% and 19.4%, respectively, which increased to 99.6% and 28.3% when combined with PET-CT.
Tumor Origin Detection: Accuracy of cfDNA-Based Tests
Systematic Review Findings
A systematic review and meta-analysis examined the accuracy of tumor origin detection using cfDNA-based multi-cancer early detection (MCED) tests. The analysis included 3,895 cancer samples and found that the accuracy of predicting the tissue of origin was 79%. Colorectal cancers had the highest accuracy, while liver and bile duct cancers had the lowest, although the differences were not statistically significant.
Methodologies
The studies reviewed used various methodologies, including methylation patterns, fragmentation profiles of cfDNA, and combinations of cfDNA mutations with protein markers, to determine the tumor origin.
PanSeer: Longitudinal Study Results
Early Detection Capabilities
The PanSeer test, based on circulating tumor DNA methylation, demonstrated the ability to detect five common cancer types up to four years before conventional diagnosis. In a study involving 605 asymptomatic individuals, PanSeer detected cancer in 95% of those who were later diagnosed, with a specificity of 96%. This indicates that PanSeer could significantly advance early cancer detection and improve patient outcomes.
Blood Markers for Colorectal Cancer
Full Blood Count (FBC) and Other Markers
A systematic review and meta-analysis of full blood count (FBC) components identified several markers associated with colorectal cancer, including red blood cells, hemoglobin, mean corpuscular volume, and white blood cell count. Additionally, other promising markers such as methylated SEPT9 DNA and interleukin 8 have shown high sensitivity and specificity for colorectal cancer detection .
Performance of Blood Markers
The performance of these markers varies, with sensitivities ranging from 70% to 98% and specificities from 84% to 98.7%. Combining these markers with other tests, such as the fecal immunochemical test (FIT), can further improve detection rates.
Conclusion
Blood-based tests for cancer detection represent a significant advancement in oncology, offering a non-invasive, accurate, and early detection method for multiple cancer types. Tests like CancerSEEK and PanSeer, along with the integration of imaging techniques like PET-CT, show great promise in improving early cancer diagnosis and patient outcomes. Further research and longitudinal studies are essential to validate these findings and integrate these tests into routine clinical practice.
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