Sigmoidoscopy screening led to reduced incidence of colorectal cancer, though more for men vs women, and a reduced rate of colorectal cancer–related mortality in men, according to findings from the randomized, controlled NORCCAP trial published in the Annals of Internal Medicine.
Background and Study Methods
Meta-analyses of randomized trials have shown that sigmoidoscopy screening can reduce the incidence of colorectal cancer and colorectal cancer–related mortality through 15 years.
Researchers in Norway conducted the randomized, controlled Norwegian Colorectal Cancer Prevention (NORCCAP) trial to assess the benefits of sigmoidoscopy screenings. Individuals between the ages of 50 and 64 years without colorectal cancer at randomization were offered a one-time sigmoidoscopy with or without fecal immunochemical testing, or no screening. Patients were followed for 23 years.
More than 100,000 individuals were randomly assigned to receive screening or not, and 98,654 individuals were included in the intention-to-screen analyses, with 20,552 in the screening cohort and 78,102 in the no-screening cohort.
Key Findings
The 23-year cumulative risk for colorectal cancer was 4.3% among men in the screening cohort and 6.0% for men in the no-screening cohort (risk difference = –1.7 percentage points; 95% confidence interval [CI] = –2.2 to –1.2 percentage points). For women, the cumulative risk was 4.2% in the screening cohort vs 4.7% in the no-screening cohort (risk difference = –0.5 percentage points; 95% CI = –1.0 to –0.01 percentage points).
For men, the cumulative risk for colorectal cancer–related mortality at 23 years was 1.4% in the screening cohort and 2.2% in the no-screening cohort (risk difference = –0.8 percentage points; 95% CI = –1.1 to –0.5 percentage points). The 23-year cumulative risk for colorectal cancer–related death in women was 1.3% in the screening cohort and 1.4% in the no-screening cohort (risk difference = –0.1 percentage points; 95% CI = –0.3 to 0.1 percentage points).
Researchers noted that differences were strongest for rectosigmoid cancer, and that the addition of fecal blood testing did not improve the benefits of screening.
The researchers believe that these findings could reduce the need for repeated sigmoidoscopy screenings within the usual screening age range.
Edoardo Botteri, PhD, of the Department of Colorectal Cancer Screening and Department of Research, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway, is the corresponding author of the Annals of Internal Medicine paper.
DISCLOSURES: Funding for the study primarily came from the Norwegian government and Norwegian Cancer Society. For full disclosures of the study authors, visit acpjournals.org.
