Risk of colorectal cancer mortality after adenoma removal differs by sex

Women appear to be at higher risk of colorectal cancer death following adenoma removal, whereas men are at lower risk, as reported in a recent study.

The study included 40,293 individuals who had adenomas removed in Norway, of whom 19,725 were women (49.0 percent) and 20,568 men (51.0 percent). The total follow-up time was 492,736 person-years (median 13.0 years), with 26,461 survivors followed for 10 years or more.

During follow-up, 1,079 women (5.5 percent) and 866 men (4.2 percent) developed colorectal cancer. Of these, 328 women and 275 men died of colorectal cancer.

Median age at first adenoma was 67.0 years, colorectal cancer diagnosis was 79.9 years, and colorectal cancer death was 80.2 years for women; the corresponding values for men were 65.4, 77.5, and 77.8 years.

Colorectal cancer incidence was much higher in women (standardized incidence ratio [SIR], 1.64, 95 percent confidence interval [CI] 1.54–1.74) than in men (SIR, 1.12, 95 percent CI, 1.05–1.19). Moreover, women had increased colorectal cancer mortality (standardized incidence-based mortality ratio [SMR], 1.13, 95 percent CI, 1.02–1.26). Men, on the other hand, had lower colorectal cancer mortality (SMR, 0.79, 95 percent CI, 0.71–0.89).

The highest risk of colorectal cancer death was documented among women with high-risk adenomas (≥2 adenomas, villous component, or high-grade dysplasia; SMR, 1.37, 95 percent CI, 1.19–1.57). Of note, women with low-risk adenomas (SMR, 0.90, 95 percent CI, 0.76–1.07) and men with high-risk adenomas had a similar risk (SMR, 0.89, 95 percent CI, 0.76–1.04), while men with low-risk adenomas had the lowest risk of colorectal cancer death (SMR, 0.70, 95 percent CI, 0.59–0.84).

The findings highlight the importance of sex-specific surveillance recommendations after adenoma removal.