How Good Is Good Enough? What Should Be the Target for CRC Screening?

Colorectal Cancer (CRC) screening of average-risk individuals has been shown to reduce CRC mortality and incidence. Incidence is reduced by detection and removal of cancer precursor lesions (CPLs), resulting in cancer prevention. Mortality reduction is achieved with detection of curable CRC, as well as prevention by removing CPLs before cancer develops. Targets of screening include both curable CRC and CPLs. Non-invasive stool tests are a multi-step screening program which can detect curable cancers and less likely to detect CPLs than invasive screening. The non-invasive programs depend on completion of colonoscopy if the test is positive. Invasive screening with colonoscopy is a one-step test program, with excellent detection of both curable CRCs and CPLs, if performed with high-quality. Current evidence suggests that either program could be effective, despite different targets. Patient adherence and program quality are perhaps the important determinants of program effectiveness.