Introduction Early detection of colorectal cancer plays an important role in patient survival. A screening program for colorectal cancer has been proven to reduce mortality from the disease. There is a growing interest in potential biomarkers to predict early colorectal cancer as current screening modalities lack compliance and specificity. The aim of this study was to systematically review the recent literature to identify all published biomarkers for early detection of colorectal cancer and polyps; to summarise performance characteristics of each biomarker and to test if they can be used for designing new screening tests for colorectal cancer.
Methods Literature searches were conducted according to PRISMA guidelines, of Medline, EMBASE and PubMed databases for relevant papers since the most recent systematic review in 2007. The review focused on human studies reporting on early detection of colorectal cancer and/or colorectal polyps using biomarkers. The studies were categorised into faecal, blood or tissue biomarkers and these were then subdivided depending on the category of marker being examined: (1) DNA biomarkers, (2) RNA biomarkers, (3) Protein biomarkers or (4) Other. Our review reported on the sensitivity and specificity of each biomarker, alongside their 95% confidence interval ranges. These values were used in conjunction with disease prevalence to obtain positive and negative predictive values.
Results The search strategy identified 3348 abstracts. 44 papers, describing a total of 9908 participants and examining 67 different tumour markers were included in this review for data extraction and analysis. Overall sensitivities for colorectal cancer detection by faecal DNA markers ranged from 53% to 87% with varying specificities, however, all above 76%. Combining DNA markers increased the sensitivity of colorectal cancer detection to 86%. A 6-gene faecal DNA panel obtained a sensitivity of 68% for adenoma detection with a high specificity of 90%. Canine scent detection of volatile organic compounds had a sensitivity of detecting colorectal cancer of 99% and specificity of 97% on a study of nearly 300 patients. A panel of serum DNA and/or RNA biomarkers provide a sensitivity and specificity above 85% for all stages of colorectal cancer. A serum 4-gene DNA panel of markers has an increased specificity of 91% for adenoma detection.
Conclusion This review has demonstrated that there are several evolving faecal and serum biomarkers that can predict colorectal cancer. When combined into biomarker panels, higher sensitivity and specificities for early detection of colorectal cancer and adenomas are achieved. Further research is required to validate these markers in a well-structured population based study.
Disclosure of Interest None Declared.
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