The predictive and prognostic value of sex in localized colorectal cancer: a SEER-based analysis

Background: Although the influence of sex on different cancer survival has been investigated, the predictive and prognostic value of sex in localized colorectal cancer (CRC) still remain controversial. Methods: Survival was evaluated in patients who diagnosed with localized CRC in the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2016. Overall survival (OS) outcomes were estimated with the Kaplan-Meier method, and multivariable Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: We obtained a dataset that included 70,836 males and 69,705 females of localized CRC patients. Compared with males, females more often had age >= 75 years (55.1% vs. 44%), right-sided colon cancer (56.8% vs. 45.4%), and more advanced pT stage cancer (75.5% vs. 72%). In addition, we found that females had better OS than males and that sex could be an independent factor of OS in T1-3N0M0 (Stage I-II) colon cancer (regardless of right/ left-sided tumour) and T1-2N0M0 (Stage I) rectal cancer (each HR <1, each P<0.05). Although a significant OS benefit was not observed in T3N0M0 rectal cancer in the overall analysis (P=0.183), females who underwent postoperative chemotherapy had better OS than males among T3N0M0 (Stage II) rectal cancer patients significantly (P<0.001). Conclusions: In our study, sex was shown to be a prognostic factor in localized-CRC. In particular, females may benefit more from postoperative chemotherapy than males with T3N0M0 (Stage II) rectal cancer.