The outcomes from a parallel randomised controlled trial have 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, ‘Long-Term Follow-up of the Italian Flexible Sigmoidoscopy Screening Trial, were 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 ten 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 six centres 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. Colorectal cancer mortality was statistically significantly reduced among men but not among women.
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.