Practical advances in stool screening for colorectal cancer

The rationale for screening for colorectal cancer (CRC) is well established, and several tests are currently recommended. Colonoscopy has become a popular modality in most of the United States and other countries. Despite colonoscopy being highly accurate and therapeutic, many patients prefer a noninvasive screening test. Testing stool for occult blood by the chemical guaiac reagent (gFOBT) has been available for decades and is effective at reducing mortality from CRC. However, because of limitations in sensitivity and specificity, newer fecal immunochemical tests (FITs) were developed that detect occult blood using enzyme immunoassays. Because of their improved sensitivity and specificity, FITs have replaced gFOBT for screening in many settings. Detecting neoplasia-associated genetic changes in stool has also become feasible; first-generation stool DNA tests showed greater sensitivity for CRC, with similar specificity to gFOBT. Improvements to stool DNA tests have made them more sensitive and less complex. As the performance characteristics for FIT and stool DNA tests continue to evolve, stool-based testing for CRC is expected to become a more reliable component in the armamentarium for CRC screening.