FS support was mainly based on three case-control studies, the earliest of which used rigid sigmoidoscopy, which confirmed that this test could reduce the mortality of colorectal cancer by 59% to 79%, but surprisingly the protective effect could continue to be effective after 16 years. At present, FS screening includes two large RCT: PLCO in the United States and FleXiScope in the United Kingdom. Sigmoidoscopy only has 60cm, and the scope of examination is limited, so it is easy to cause missed diagnosis.
It is worth noting that if the lesion is found and removed by FS, it is necessary to do a full colonoscopy. ACS recommends that if a high-risk lesion is found in the distal colon, a full colonoscopy should be performed regardless of whether it is resected or not. ASGE believes that no matter what lesions are found, further colonoscopy should be done. At present, there is still no evidence of evidence-based medicine that FS once every 5 years combined with FOBT once a year can better reduce the mortality of colorectal cancer than once a year FOBT alone.
