Abstract: Background and purpose: Small bowel adenocarcinoma (SBA) is uncommon, and frequently diagnosed at late stage. Chemotherapy is the main treatment method for advanced SBA. Despite recent progress in SBA therapy, no standard regimen has been established up to now, and new active regimen is expected to improve the outcome of this disease. The purpose of this study was to evaluate the efficacy and safety of S-1/oxaliplatin for the treatment of advanced SBA. Methods: In a retrospective study, clinical characteristics and outcomes of 29 patients with advanced SBA were collected and analyzed. Patients received oral S-1 40 mg/m², twice daily, d1-14, oxaliplatin was administered intravenously 130 mg/m² on the first day of every cycle, repeated every 3 weeks. Efficacy and toxicity were evaluated after at least two consecutive cycles. Results: All patients were evaluated for efficacy and safety. The objective response and disease control rates were 37.9% and 65.5%, respectively. The median progression-free survival and overall survival were 5.4 months (95%CI: 3.6-7.2) and 13.2 months (95%CI: 6.7-19.7), respectively. In univariate analysis, the following factors were significantly associated with poor outcome: not first line chemotherapy setting, ECOG performance status>1 and sites of metastasis>2 (Log-rank, P<0.05). The treatment related adverse events were mild and manageable. Myelosuppression, gastrointestinal reaction, fatigue, sensory neuropathy and rash were the most common toxicities. Conclusion: This study was the first to report the efficacy of S-1 combined with oxaliplatin for advanced SBA. S-1/oxaliplatin may be effective and safe for advanced SBA and worthy of further study.

Key words: Advanced small bowel adenocarcinoma, Chemotherapy, S-1, Oxaliplatin