Colorectal Cancer Risk Lower at 10 Years in Patients Invited to Undergo Screening Colonoscopy

Individuals who were invited to undergo screening colonoscopy had a lower risk for colorectal cancer (CRC) at 10 years compared with those who were assigned to no screening, according to a study in the New England Journal of Medicine.

Investigators reported findings from the randomized Nordic-European Initiative on Colorectal Cancer (NordICC) trial (ClinicalTrials.gov Identifier: NCT00883792) that examined the effects of population-based colonoscopy screening on the risk for CRC and related death at 10 years. The trial was conducted in Poland, Norway, Sweden, and the Netherlands and included men and women aged 55 to 64 years who had not previously undergone screening.

Participants were identified from population registries and were randomly assigned 1:2 either by invitation to undergo colonoscopy screening (the invited group) or by no invitation and no screening (the usual care group).

The primary endpoints were the risk for CRC and death from CRC after a median follow-up of 10 to 15 years.

A total of 84,585 participants were included (invited group, n=28,220; usual care group, n=56,365) in the study. The overall median age at randomization was 59 years, and 50.1% were men. The median follow-up in the current analysis was 10.0 years in both groups (IQR, 9.9-10.0 years).

CRC was diagnosed at screening in 62 participants (0.5%), and 15 (0.13%) had polypectomy-related major bleeding. All cases of bleeding were treated endoscopically, and no perforations or screening-related deaths occurred within 30 days.

At 10 years, the risk for CRC was 0.98% (259 cases) in the invited group and 1.20% (622 cases) in the usual care group (risk ratio [RR], 0.82; 95% CI, 0.70-0.93). The number needed to invite to undergo screening to prevent 1 case of CRC within 10 years was 455 (95% CI, 270-1429).

The risk at 10 years for CRC-related death was 0.28% (72 deaths) in the invited group and 0.31% (157 deaths) in the usual care group (RR, 0.90; 95% CI, 0.64 to 1.16). In the 10-year follow-up, 3036 participants in the invited group (11.03%) died from any cause compared with 6079 (11.04%) in the usual care group (RR, 0.99; 95% CI, 0.96-1.04).

The risk for CRC at 10 years was reduced from 1.22% to 0.84% in adjusted analyses to estimate the effect of screening if all the participants who were randomly assigned to screening had actually undergone screening. The corresponding estimated RR was 0.69 (95% CI, 0.55-0.83). Participants in the invited group had 0.15% risk for death from CRC vs 0.30% in the usual care group, with an estimated RR of 0.50 (95% CI, 0.27-0.77).

Study limitations include lower than-expected participation in some countries and a lack of information about adherence to recommendations in surveillance for polyps. Also, variation in quality indicators among endoscopists may have resulted in differences in the detection of cancer after screening, although event rates were too small to further analyze. Furthermore, longer follow-up may be needed to determine the full effect of colonoscopy screening.

“Our results may serve to quantify the effectiveness of screening colonoscopy for the prevention of colorectal cancer and thus enable decision makers to properly prioritize resources for cancer screening and health care services,” the study authors noted.

Disclosure: Some of study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.