Cumulative FIT rounds detect CRC, advanced adenomas better than sigmoidoscopy

Repeated faecal immunochemical testing (FIT) leads to greater detection of colorectal cancer (CRC) and advanced adenomas compared with once-only sigmoidoscopy, as shown in a study.

The study included individuals aged 50–74 years living in Southeast Norway. They were randomly invited to undergo either once-only flexible sigmoidoscopy or FIT screening every second year. Colonoscopy was recommended after sigmoidoscopy if any polyp of ≥10 mm, ≥3 adenomas, any advanced adenomas, or CRC was found or, subsequent to, FIT >15 μg haemoglobin/g faeces.

A total of 139,291 individuals were included: 69,195 were randomized to sigmoidoscopy and 70,096 to FIT. The participation rate was 52 percent for sigmoidoscopy, 58 percent in the first FIT round, and 68 percent for three cumulative FIT rounds.

Compared with sigmoidoscopy, the detection rate for CRC did not differ in the first FIT round (0.25 percent vs 0.27 percent; odds ratio [OR], 0.92, 95 percent confidence interval [CI], 0.75–1.13) but higher after three FIT rounds (0.49 percent vs 0.27 percent; OR, 1.87, 95 percent CI, 1.54–2.27).

Meanwhile, advanced adenoma detection rate was lower in the first FIT round relative to sigmoidoscopy (1.4 percent vs 2.4 percent; OR, 0.57, 95 percent CI, 0.53–0.62) but higher after three cumulative FIT rounds (2.7 percent vs 2.4 percent; OR, 1.14, 95 percent CI, 1.05–1.23).

In terms of safety, the risk of perforation and bleeding was comparable. Serious adverse events occurred in 33 patients (0.05 percent) in the sigmoidoscopy group and 47 (0.07 percent) in the FIT group (p=0.13).