Sex-Specific Differences in Colon Cancer when Quality Measures Are Adhered to: Results from International, Prospective, Multicenter Clinical Trials.

Abstract

There is no consensus on the relationship between patient sex and the location, stage, and oncologic outcome of colon cancer (CC). We hypothesized that there is a sex-specific difference in the biology and management of CC. Our cohort was drawn from a database of patients enrolled in international trials of nodal ultrastaging for nonmetastatic CC. These trials required strict adherence to surgical and pathologic quality measures. Postoperative follow-up included colonoscopy at 1 and 4 years and annual CT scans. Sex-specific differences in tumor biology, location, stage, and recurrence were evaluated by chi-square, Fischer's exact, and independent t-tests. The cohort included 435 males (median age 69 years) and 423 females (median age 70 years). Females had more right-sided (p = 0.03) and earlier T stage (p = 0.05) tumors, but there was no sex-based difference in pathologic grade, total lymph nodes retrieved, nodal positivity (p = 0.47) or lymphovascular invasion (p = 0.45). The overall 4-year disease-free survival (DFS) was comparable in females and males (77.9% and 77.5%, respectively). By multivariate analysis, only nodal positivity and cancer recurrence affected overall survival (OS) (p = 0.008). Neither sex nor primary tumor affected DFS or OS. This is the first prospective study to demonstrate sex-specific differences in location and T stage of CC when surgical and pathologic management adhered to strict quality standards. The predominance of right-sided CC in females suggests that flexible sigmoidoscopy may be inadequate for screening and surveillance. Interestingly, earlier stage and right-sided location did not confer a DFS or OS advantage for women. Additional studies are needed to determine why females have a higher propensity for right-sided lesions and a potential difference in CC biology.