Blood tests for colorectal cancer screening in the standard risk population.

Barriers to screening for colorectal cancer (CRC) might be circumvented by using a blood test. New blood markers continue to be discovered, comprising RNA, DNA, and protein. On reviewing the literature on biomarkers in blood, many potentially valuable markers have been described. Those based on DNA have been the best evaluated to date and are not subject to the same specificity problems as fecal immunochemical tests (FIT), but as a class have relatively poorer sensitivity for adenomas. Most other markers have not been taken beyond the most rudimentary clinical assessment, and extremely few have been assessed in the screening context relative to proven screening tests such as FIT and colonoscopy. Adoption of blood tests into screening programs is going to depend on clarification of adequate accuracy for targeted neoplastic lesions in the screening environment and their relative performance and acceptability to existing proven tests.