658 BETTER SURVIVAL IN FEMALES THAN MALES AFTER RESECTION OF OESOPHAGEAL OR GASTROESOPHAGEAL JUNCTION CANCER: A COHORT STUDY IN SWEDEN

Accumulating evidence points to a better survival in female patients after a curative oesophageal cancer surgery. However, there is a need for more well-designed and sufficiently powered studies for limitations in previous studies. Better understanding of sex differences in the postoperative survival may be helpful for a sex-specific treatment. Methods This is a population-based cohort study including all patients in Sweden with oesophageal cancer that underwent a curative surgical treatment between 2006 and 2017. Sex difference in postoperative survival was explored with excess mortality rate ratio (EMRR) and absolute difference of excess mortality rate along the whole follow-up time, using flexible parametric model. Age at the time of surgery, Charlson comorbidity index, ASA score, tumor stage, post-operative complications, marital status, education level and hospital volume were considered as covariates in the analysis model. Stratification analysis by clinical stages, perioperative neoadjuvant treatment and post-operative complications was also performed. Results In all, there were 1301 patients resected for oesophageal adenocarcinoma and 305 patients for oesophageal squamous cell carcinoma. For both oesophageal adenocarcinoma and oesophageal squamous cell carcinoma, female patients had a lower excess mortality rate than males (adjusted EMRR: 0.77, 95% CI: 0.58–1.01, P = 0.059; 0.53, 95% CI: 0.33–0.85, P = 0.009, respectively). This sex difference was particularly strong shortly after surgery then gradually decreased over the ensuing years (Figure) and was more profound in the early clinical stages, and in patients receiving neoadjuvant treatment and without post-operative complications. Conclusion Female patients seem to have a better survival shortly after esophagectomy for patients with oesophageal adenocarcinoma and oesophageal squamous cell carcinoma, and the sex difference thereafter weakened. Our results may imply a different response to oesophageal cancer surgery between the sexes, and associated pre- and post-operative treatment, thus a sex-specific strategy may be considered in further work.