A Fourth Randomized, Controlled Trial of Flexible Sigmoidoscopy Screening

Three previous trials from the U.K., Italy, and the U.S. have demonstrated that flexible sigmoidoscopy reduces distal colorectal cancer (CRC) incidence and mortality.

In a fourth trial from Norway, 98,792 asymptomatic persons were randomized to receive no screening (78,220), flexible sigmoidoscopy (10,283), or flexible sigmoidoscopy plus guaiac-based fecal occult blood test (FOBT; 10,289).

Adherence was higher in the flexible-sigmoidoscopy-only group compared with the flexible-sigmoidoscopy-plus-FOBT group (65.1% vs. 60.9%; P<0.001). Based on intention to screen, CRC incidence was reduced by 20% overall, 32% in the 50-to-54-year age group, 17% in the 55-to-64-year age group, 27% in men, and 13% in women. Distal CRC incidence reduction was 24%…