If there is one screening test in medicine that has earned the right to be called "lifesaving", it is colonoscopy for colorectal cancer. The evidence base is large, and the intervention is both diagnostic and therapeutic: precancerous polyps can be found and removed in the same session.
And yet, about a third of Americans aged 45 to 75 have never had any colorectal cancer screening at all.
The numbers
Colorectal cancer is the second leading cause of cancer death worldwide. But unlike most cancers, it develops slowly — typically over 10 to 15 years — through a predictable sequence: normal tissue → polyp → advanced polyp → cancer. That is why screening works: the sequence can be interrupted years before cancer develops.
The 1993 Winawer study showed that removing adenomatous polyps during colonoscopy reduced colorectal cancer incidence by 76–90% compared with reference groups. The randomised NordICC trial (2022) is more sober: among all invitees (only 42% attended), CRC deaths fell by a non-significant 10% after 10 years; among those actually screened, by about 50%. Observational cohorts report roughly 68% lower CRC mortality.
Why 45 — and who needs it earlier
The USPSTF updated its recommendation in 2021 to start screening at age 45, down from the previous recommendation of 50. This change was driven by a concerning trend: rising rates of colorectal cancer in younger adults — the American Cancer Society reported a 51% increase in people under 50 since 1994. Rules differ by country: in Germany, statutory insurance covers screening colonoscopy from 50 for women and men.
Some people need screening even earlier:
- First-degree relative with CRC before age 60: begin at 40, or 10 years before the relative's age at diagnosis if earlier
- Known Lynch syndrome: begin at 20–25; classic familial adenomatous polyposis: begin around age 10–12
- Personal history of inflammatory bowel disease: begin 8 years after diagnosis
If any of these apply, it is worth raising with your own physician well before the standard start age.
What the experience is actually like
Most people dread colonoscopy, but the procedure is straightforward. You arrive fasting, receive sedation (in Germany, typically propofol — you are fully asleep), and the gastroenterologist examines the colon with a flexible scope. The entire procedure takes 20–30 minutes. If polyps are found, they are removed during the same session and sent for histopathology.
The part people actually dislike is the preparation — drinking a bowel-cleansing solution the day before. It is unpleasant — but one afternoon of discomfort for a test that can prevent cancer is a clear trade-off.
If no polyps are found, the next colonoscopy is typically in 10 years. If adenomas are found, the interval depends on number, size and histology — in US recommendations (2020), 7–10 years for one or two small tubular adenomas, 3 years for advanced or numerous ones.
Questions to ask before your colonoscopy
Is the procedure performed by an experienced, board-certified gastroenterologist, and what is their adenoma detection rate? What kind of sedation is used? Will any polyps be removed in the same session, and are there extra costs for polyp removal? How and when will the pathology results be communicated — and when is the next examination due based on those results?
References
- Winawer SJ, et al. Prevention of colorectal cancer by colonoscopic polypectomy. N Engl J Med. 1993;329:1977-1981.
- Bretthauer M, et al. Effect of colonoscopy screening on risks of colorectal cancer and related death (NordICC). N Engl J Med. 2022;387:1547-1556.
- Davidson KW, et al. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(19):1965-1977.
- Nishihara R, et al. Long-term colorectal-cancer incidence and mortality after lower endoscopy. N Engl J Med. 2013;369(12):1095-1105.
- Rex DK, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030.
- Gupta S, et al. Recommendations for follow-up after colonoscopy and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2020;115(3):415-434.
- Rex DK, et al. Quality indicators for colonoscopy. Am J Gastroenterol. 2024;119:1754-1780.
- King SC, et al. Baseline estimates of colorectal cancer screening among adults aged 45 to 75 years, Behavioral Risk Factor Surveillance System, 2022. Prev Chronic Dis. 2025;22:250175.
This article is general information and not individual medical advice. Decisions about tests and treatment belong in a conversation with your own physician.