Starting colorectal cancer screening at ages 45–50: use fecal immunochemical tests or colonoscopies

Fecal tests cost just a few dozen yuan and can be done every 1–2 years. Colonoscopies cost several hundred to over a thousand yuan; those with negative results only need one every 10 years. Preparing for a colonoscopy requires setting aside a full day for bowel cleansing.

Cochrane pooled data from multiple studies showing that individuals undergoing fecal occult blood screening have a roughly 16% lower risk of dying from colorectal cancer. The original RR was 0.84, with a 95% CI ranging from 0.78 to 0.90. For those who’ve had at least one screening round, this risk reduction reaches 25% (RR 0.75). The NordICC randomized trial likewise found that among participants invited to get a colonoscopy, colorectal cancer incidence dropped from 1.20% to 0.98% over 10 years; its RR was 0.82, with a 95% CI of 0.70–0.93.

Hewitson P 等 (2007). Screening for colorectal cancer using the faecal occult blood test, Hemoccult. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD001216.pub2 ; Bretthauer M 等 (2022). Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death. New England Journal of Medicine. https://doi.org/10.1056/NEJMoa2208375

Controversy. NordICC is calculated based on people "invited to undergo colonoscopy." Colorectal cancer mortality was 0.28% vs 0.31% (RR 0.90, 95% CI 0.64 to 1.16), which is within the margin of error. This indicates that the benefits of colonoscopy for mortality rates may have been previously overestimated. Evidence for fecal testing regarding mortality is actually more robust. Regarding the age to start screening, international guidelines range between 45 and 50 years old. Those with a family history of this disease should start earlier. For those who have already developed colon cancer and completed surgery and chemotherapy, guidance on exercise is in Section 16, Item 14 (Post-surgery and chemotherapy for colon cancer).