Is There a Sex Effect in Colon Cancer? Disease Characteristics, Management, and Outcomes in Routine Clinical Practice

Introduction: The incidence of colon cancer varies by sex. Whether women and men show differences in extent of disease, treatment, and outcomes is not well described. We used a large population-based cohort to evaluate sex differences in colon cancer. Methods: Using the Ontario Cancer Registry, all cases of colon cancer treated with surgery in Ontario during 2002–2008 were identified. Electronic records of treatment identified use of surgery and adjuvant chemotherapy. Pathology reports for a random 25% sample of all cases were obtained, and disease characteristics, treatment, and outcomes in women and men were compared. A Cox proportional hazards model was used to identify factors associated with overall (os) and cancer-specific survival (css). Results: The study population included 7249 patients who underwent resection of colon cancer; 49% (n = 3556) were women. Stage of disease and histologic grade did not vary by sex. Compared with men, women were more likely to have right-sided disease (55% vs. 44%, p ≤ 0.001). Surgical procedure and lymph node yield did not differ by sex. Adjuvant chemotherapy was delivered to 18% of patients with stage ii and 64% of patients with stage iii disease; when adjusted for patient- and disease-related factors, use of adjuvant chemotherapy was similar for women and men [relative risk: 0.99; 95% confidence interval (ci): 0.94 to 1.03]. Adjusted analyses demonstrated that os [hazard ratio (hr): 0.80; 95% ci: 0.75 to 0.86] and css (hr: 0.82; 95% ci: 0.76 to 0.90) were superior for women compared with men. Conclusions: Long-term survival after colon cancer is significantly better for women than for men, which is not explained by any substantial differences in extent of disease or treatment delivered.