Flexible sigmoidoscopy screening associated with long-term reduction in colorectal cancer incidence and mortality

A parallel randomized controlled trial confirmed that a single flexible sigmoidoscopy screening at age 55 to 64 years represents a safe and effective strategy associated with a substantial reduction in colorectal cancer (CRC) incidence and mortality. The strong protective effect was maintained up to 15 years and 19 years, respectively. The findings are published in Annals of Internal Medicine.

Large, randomized trials of flexible sigmoidoscopy screening had shown a substantial reduction in CRC incidence (range, 18% to 26%) and mortality (range, 22% to 31%) after a median follow-up of 10 to 12 years in the intention-to-treat analysis. The recent reports of the extended incidence and mortality follow-up from three of those trials showed that the screening effect was maintained up to 15 to 17 years. Additional data about the duration of the protection conferred by a single sigmoidoscopy screening and about differences of screening effect by sex and age could offer useful insight to support evidence-based recommendations about screening intervals as well as about alternative strategies aimed to achieve a larger protective effect.

Researchers from University Hospital Città della Salute e della Scienza, Turin, Italy, randomly assigned 34,272 persons aged 55 to 64 at 6 centers in Italy to receive either a once-only flexible sigmoidoscopy screening or usual care (control group). Compared to the control group, colorectal cancer incidence was 19% lower at 15 years and CRC mortality was 22% lower 19 at years, respectively, after a single screening sigmoidoscopy. Consistent with previous estimates on the basis of the 11-year follow-up, more than 80% of averted deaths are attributable to the prevention of incident CRC via adenoma removal at screening. These findings confirm the strong preventive effect of flexible sigmoidoscopy screening.