Second-line Chemotherapy for Previously Treated Metastatic Small Bowel Adenocarcinoma: A Retrospective Analysis

Background/Aim: Metastatic small bowel adenocarcinoma (SBA) is a rare disease with poor prognosis. This study aimed to explore the efficacy and safety of secondline chemotherapy for patients with SBA. Patients and Methods: We retrospectively reviewed the clinical characteristics of 27 metastatic patients with SBA after progression on first-line chemotherapy. The patients were divided into Cohort A, receiving second-line chemotherapy, and Cohort B, receiving best supportive care. Results: Patients in Cohort B had higher age, worse performance status, and higher neutrophil-to-lymphocyte ratio compared with those in Cohort A. Cohort A showed significantly better overall survival (OS) compared with Cohort B (median OS, 15.6 vs. 3.4 months; p=0.002). Objective response rate, disease control rate, and median progression-free survival (PFS) for Cohort A were 7%, 74%, and 5.0 months, respectively. Patients who underwent irinotecan-based chemotherapy showed longer PFS and OS compared with those who underwent taxane-based chemotherapy. No significant adverse events were reported. Conclusion: Second-line chemotherapy for metastatic SBA demonstrated clinical activity with acceptable toxicities.