Is fecal occult blood testing more sensitive for left- versus right-sided colorectal neoplasia? A systematic literature review

Owing to its slow development from removable precursor lesions and early cancer stages with good prognosis, screening for colorectal cancer holds potential to reduce both the incidence and mortality of the disease. While sigmoidoscopy only detects left-sided neoplasia, there is accumulating evidence that colonoscopy is also more effective in protecting from neoplasia in the left versus the right colon and rectum. In this context, it is an important question whether the sensitivity of the most common noninvasive screening tool for colorectal cancer, fecal occult blood testing (FOBT), also differs for left- versus right-sided neoplasia. Therefore, we systematically searched the literature for prospective screening studies conducted in average-risk adults that performed FOBT (immunochemical and/or guaiac-based) and colonoscopy among all participants, and reported site-specific sensitivities of FOBT for advanced colorectal neoplasia. Most of the seven included studies showed a higher sensitivity of FOBT for advanced neoplasia in the left versus right colon, but this finding needs to be confirmed since the available literature is scarce and not entirely consistent.