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

Colorectal cancer incidence and mortality were reduced by about 20% in patients who were randomized to receive once-only flexible sigmoidoscopy screening between the ages of 55 to 64 years instead of usual care.

One sigmoidoscopy screening between the ages of 55 to 64 years represents a safe and effective strategy, providing substantial reduction in colorectal cancer incidence and mortality, a study found.

Italian researchers randomized 34,272 patients ages 55 to 64 years at six centers to receive either once-only flexible sigmoidoscopy screening or usual care. Patients were recruited from 1995 to 1999 and followed until 2012 for cancer incidence and 2014 to 2016 for death. Results were published Nov. 9 by Annals of Internal Medicine.

In patients who got sigmoidoscopy, colorectal cancer incidence was reduced by 19% (rate ratio [RR], 0.81; 95% CI, 0.71 to 0.93) in the intention-to-treat analysis and by 33% (RR, 0.67; 95% CI, 0.56 to 0.81) in the per protocol analysis. Death from colorectal cancer was reduced with the intervention screening by 22% (RR, 0.78; 95% CI, 0.61 to 0.98) in the intention-to-treat analysis and by 39% (RR, 0.61; 95% CI, 0.44 to 0.84) in the per protocol analysis. Colorectal cancer incidence was statistically significantly reduced among both men and women. In the intention-to-treat analyses, colorectal cancer mortality was statistically significantly reduced among men (RR, 0.73; 95% CI, 0.54 to 0.97) but not among women (RR, 0.90; 95% CI, 0.59 to 1.37).

The study authors noted that more than 80% of deaths that are averted by colorectal cancer screening are attributable to the prevention of cancer via adenoma removal at screening and that these findings confirm the strong preventive effect of flexible sigmoidoscopy screening.

An editorial said that this and similar studies establish a benefit of screening far beyond the currently recommended screening intervals. “Guideline makers may consider prolonging recommended screening intervals for sigmoidoscopy and colonoscopy,” according to the editorial. “Longer intervals result in lower costs as well as reduced harms and burdens through less exposure to screening and surveillance endoscopy and may not substantially compromise the benefit of screening. This may be especially relevant to persons at the lower end of the screening age where cancer risk is smaller and absolute benefits more marginal.”