AimNo studies have been published on the relationship between marital status and outcomes in small intestinal cancers. The present study was conducted to explore the influence of marital status on small intestinal adenocarcinoma survival based on the Surveillance, Epidemiology, and End Results (SEER) database.MethodsData from eligible patients diagnosed with small intestinal adenocarcinoma between 2004 and 2015 were extracted from the SEER database. Patients were categorized into married group (including common law) and unmarried group (including single [never married], widowed, divorced, separated, and unmarried or domestic partner). The primary endpoints were 5-year overall survival (OS) and 5-year cancer-specific survival (CSS). A survival curve was generated by the Kaplan–Meier method, and the survival rate differences were estimated by a log-rank test. A multivariate Cox proportional hazard model was used to evaluate the independent risk factors for survival.ResultsA total of 6,747 small intestinal adenocarcinoma patients were enrolled, including 3,862 married and 2,885 unmarried patients. The 5-year OS and 5-year CSS were significantly greater in married patients than in unmarried patients (27.1 vs 18.8% for OS and 45.7 vs 39.3% for CSS, both P<0.001). After adjusting for age, insurance status, tumor primary site, TNM stage, tumor grade, tumor histology, and surgery, the multivariate Cox proportional hazards model showed that marriage is an independent protective factor for OS (HR =0.789, 95% CI: 0.745–0.836, P<0.001) and CSS (HR =0.794, 95% CI: 0.736–0.857, P<0.001).ConclusionMarried small intestinal adenocarcinoma patients have better OS and CSS than unmarried patients. Psychological and economic supports from the spouses of married patients may contribute to improvements in survival.