Colonoscopy in colorectal-cancer screening for detection of advanced neoplasia.

Background: Recommendations for colorectal-cancer screening are based solely on age and family history of cancer, not sex.

Methods: We performed a cross-sectional analysis of the data from a large colonoscopy-based screening program that included 50,148 participants who were 40 to 66 years of age. People 40 to 49 years of age were eligible only if they had a family history of cancer of any type. Of the 43,042 participants 50 to 66 years of age, 13.3% reported a family history of colorectal cancer, as did 66.3% of the 7106 participants who were 40 to 49 years of age. We defined advanced neoplasia as cancer or adenoma that was at least 10 mm in diameter, had high-grade dysplasia, or had villous or tubulovillous histologic characteristics, or any combination thereof. We used multivariate logistic regression to identify associations between participants' characteristics and advanced neoplasia in a primary (or derivation) data set, and we confirmed the associations in a secondary (or validation) data set.

Results: Advanced neoplasia was detected in 2553 (5.9%) participants 50 to 66 years of age and in 243 (3.4%) participants 40 to 49 years of age. The rate of complications during colonoscopy was 0.1%, and no participants died. In the validation set, a logistic-regression model showed that male sex was independently associated with advanced neoplasia (adjusted odds ratio, 1.73; 95% confidence interval, 1.52 to 1.98; P<0.001). In each age group (40 to 49 years, 50 to 54 years, 55 to 59 years, and 60 to 66 years), the number of persons who would have to undergo colorectal-cancer screening in order to detect one advanced neoplasia was significantly lower in men than in women (23 vs. 36, 17 vs. 28, 12 vs. 22, and 10 vs. 18, respectively).

Conclusions: We detected advanced neoplasia at a significantly higher rate in men than in women, which may warrant refinement of the screening recommendations for colorectal cancer.