Clinical Question

Is fecal immunochemical testing (FIT) an effective method of screening for colorectal cancer?

Bottom Line

FIT every other year, over at least six years, identified fewer cancers and advanced adenomas initially, but surpassed a single sigmoidoscopy in detection after three rounds of testing. The increased detection may be because of greater participation in FIT than in sigmoidoscopy. (Level of Evidence = 1b)

Synopsis

Using a national patient registry in two geographic areas of southeast Norway, the investigators randomly invited individuals 50 to 74 years of age (N = 139,291) for either a once-only screening with flexible sigmoidoscopy or FIT every other year for a maximum of four rounds. None of the patients who received an invitation to this study had ever undergone any colorectal cancer screening. Positive findings with either screening were confirmed by colonoscopy. More patients accepted the invitation for screening via FIT (58.4% in the first round and 68.4% after three cumulative rounds) compared with sigmoidoscopy (52.1%). Patients with a 10-mm or larger polyp or at least three adenomas with dysplasia or villous architecture were referred for colonoscopy. Sigmoidoscopy identified more stage I colorectal cancer than FIT (odds ratio = 0.72; 95% CI, 0.55 to 0.95), although overall identification of colorectal cancer was similar between the two means of screening. Colorectal cancer detection rates were higher after three cumulative rounds of FIT (0.49% vs. 0.27%), and the difference was particularly pronounced for lesions located in the proximal colon. Advanced adenoma detection rates were higher with sigmoidoscopy for the first two rounds of FIT but were better with FIT after three rounds. False positives cannot be calculated because not all screened participants had a colonoscopy. FIT may result in a higher diagnostic yield because patients were solicited up to four times whereas patients assigned to sigmoidoscopy were solicited just once, and more patients (68%) who were offered FIT received at least one screening compared with only 52% for sigmoidoscopy.

Study design: Randomized controlled trial (nonblinded)

Funding source: Government

Allocation: Concealed

Setting: Population-based

Reference: Randel KR, Schult AL, Botteri E, et al. Colorectal cancer screening with repeated fecal immunochemical test versus sigmoidoscopy: baseline results from a randomized trial. Gastroenterology. 2021;160(4):1085–1096.e5.

Editor's Note: Dr. Shaughnessy is an assistant medical editor for AFP.