Sex-specific differences in colorectal cancer: A multicenter retrospective cohort study

Background: Due to sex-specific differences in the incidence and clinical and histopathological characteristics of colorectal cancer (CRC), understanding the impact of sex on CRC may suggest sex-targeted strategies for screening, treatment, and prevention, leading to improved prognosis of CRC. However, there have been few studies investigating the sex-specific differences in CRC in the Republic of Korea. We aimed to assess sex differences in CRC in the Republic of Korea. Methods: This was a retrospective, multicenter, cohort study of patients diagnosed with CRC between January 2012 and December 2013 at nine hospitals. Patients who had an uncertain CRC stage, were diagnosed with other cancers within 5 years, had carcinoma in situ, non-epithelial cancer, or primary cancer other than CRC, were excluded. Factors associated with overall survival or progression-free survival were investigated using Cox regression analysis. Cumulative probability of metachronous lesions was compared using the Kaplan–Meier estimator survival analysis and we compared the survival curves of each group using a log-rank test. Outcomes were compared using the chi-square, Fisher's exact, or Student's t-test, as appropriate. Results: Three thousand one hundred and forteen patients (1999 men, 1315 women) were included. There was no significant difference in the age at onset between men and women. The proportion of patients diagnosed through regular health check-ups, and asymptomatic at time of diagnosis, was higher in men (48.9% men vs. 42.0% women, p <.001). Rectal cancers were more common in men (38.8% men vs. 31.8% women, p <.001). Right colon cancers were more common in women (31.4% women vs. 22.7% men, p <.001). KRAS mutations were found in 109/317 (34.4%) women and 112/480 (23.3%) men. Overall CRC survival and progression-free survival were similar in both sexes. Conclusion: Sex differences in CRC may be due to the biological and social-behavioral differences between the sexes. They should be considered during screening, diagnosis, and treatment of CRC for better outcomes.