Twenty-Three-Year Benefits of Sigmoidoscopy Screening for Colorectal Cancer : A Randomized Trial

Area of Science:

• Oncology
• Preventive Medicine
• Gastroenterology

Background:

• Previous meta-analyses confirmed sigmoidoscopy screening benefits for colorectal cancer (CRC) incidence and mortality up to 15 years.
• The long-term impact of sigmoidoscopy screening on CRC outcomes requires further investigation.

Purpose of the Study:

• To evaluate the 23-year benefits of sigmoidoscopy screening for colorectal cancer.
• To assess the impact of sigmoidoscopy, with or without fecal immunochemical testing, on CRC incidence and mortality.

Main Methods:

• A randomized controlled trial (NORCCAP) involving 100,210 participants aged 50-64 years without CRC at randomization.
• Participants were assigned to once-only sigmoidoscopy screening (with or without fecal immunochemical testing) or no screening.
• Long-term follow-up for CRC incidence and death was conducted through national registries.

Main Results:

• Over 23 years, sigmoidoscopy screening reduced CRC incidence by 1.7 percentage points in men and 0.5 percentage points in women.
• CRC mortality was reduced by 0.8 percentage points in men but showed no significant reduction in women.
• The screening benefits were most pronounced for rectosigmoid cancers, and adding fecal blood testing did not enhance these benefits.

Conclusions:

• Sigmoidoscopy screening in Norway demonstrated a significant long-term reduction in CRC incidence and mortality, particularly in men.
• The study highlights a differential effect of screening based on sex, with greater benefits observed in men.
• These findings support the role of sigmoidoscopy in long-term CRC prevention strategies, especially for men.