Fecal Occult Blood Testing in Colorectal Cancer Screening
Summary
Fecal occult blood testing (FOBT) is a non-invasive screening tool designed to detect hidden blood in stool as an early indicator of colorectal neoplasia. Employed widely in organised screening programmes, FOBT encompasses both chemical (guaiac-based) and immunochemical methods. The guaiac-based test relies on the peroxidase activity of haem, whereas immunochemical assays detect human globin via specific antibodies. Advances in quantitative immunochemical FOBT have enabled objective threshold setting, improving sensitivity while requiring careful balance to maintain specificity. As a first-line population screening modality, FOBT offers high participation rates, cost-effectiveness and minimal risk, facilitating detection of early-stage cancers and precancerous lesions such as adenomas. However, performance is influenced by dietary factors, concomitant medications and bleeding from non-colorectal sources, which can yield false positives or negatives. Integration with follow-up colonoscopy or flexible sigmoidoscopy is essential to confirm findings and guide management. Globally, screening protocols vary in test type, threshold selection and sampling frequency, but the overarching goal remains consistent: reduce colorectal cancer mortality through early detection and intervention.
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Fecal Occult Blood Testing in Colorectal Cancer Screening publication trend
The graph below shows the total number of articles in fecal occult blood testing in colorectal cancer screening across all publications each year (not limited to Nature Index journals).
Technical terms
Faecal occult blood test (FOBT): A non-invasive assay detecting hidden blood in stool, used for colorectal cancer screening.
Guaiac-based FOBT: A chemical method in which plant-derived guaiac reagent oxidises in the presence of haem peroxidase, indicating blood.
Immunochemical FOBT (iFOBT): A test employing antibodies to detect human haemoglobin, offering greater specificity for lower gastrointestinal bleeding.
Quantitative immunochemical FOBT: An iFOBT variant that measures haemoglobin concentration in stool, allowing adjustable thresholds and objective reporting.
Adenoma: A benign glandular tumour of the colon that can serve as a precursor to colorectal cancer.
References
- Association of ten gastrointestinal and other medical conditions with positivity to faecal occult blood testing in routine screening: a large prospective study of women in England. International Journal of Epidemiology (2019).
- Feasibility of Support by Family Practitioners in Reducing Colorectal Cancer-Related Death among Outpatients Who Have Not Undergone Colorectal Cancer Screening. Diagnostics (2022).
- Fecal occult blood testing in colorectal cancer screening programs. Research and Practical Medicine Journal (2022).
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