One sigmoidoscopy significantly reduces long-term CRC incidence in both men and women

A pooled analysis evaluating the 15-year effect of sigmoidoscopies has found that receiving one sigmoidoscopy significantly reduces long-term incidence of colorectal cancer (CRC) in both men and women. The analysis is published in Annals of Internal Medicine.

Colorectal cancer is the third most common cancer worldwide, with more than 1.9 million new cases and more than 930,000 deaths each year. Sigmoidoscopy and colonoscopy screening provide an opportunity for CRC reduction by detecting early cancer and removing premalignant polyps. However, there has been uncertainty as to how long the benefits of sigmoidoscopy screening lasts, and whether the benefits differ by sex.

Researchers from Norway, the United States, Italy and the United Kingdom conducted an analysis of four randomized trials comprising more than 274,000 participants over a follow-up period of minimum 15 years comparing sigmoidoscopy screening to usual care. The data showed that persons screened at least once experienced a 21% reduction in CRC incidence compared to usual care.

The data also showed that receiving at least one screening reduced CRC-related mortality by 20% and all-cause mortality by 2%. The CRC incidence varied by gender, with men experiencing a 25% incidence reduction and women experiencing a 16% incidence reduction.

According to the authors, possible explanations for the CRC incidence difference between men and women include differences in the quality of bowel preparation, more technically challenging procedures in women, and a higher incidence and larger proportion of proximal colon cancer in women.