Effectiveness of Palliative Chemotherapy and Associated Prognostic Factors in Advanced Small Bowel Adenocarcinoma: A Propensity Score-Matched Analysis

Abstract

Purpose: Small bowel adenocarcinoma (SBA) is a rare gastrointestinal malignancy with limited evidence guiding systemic treatment in the advanced stages. This study evaluated the effectiveness of palliative chemotherapy and revealed the prognostic factors associated with survival in patients with metastatic or unresectable SBA. Patients and Methods: We conducted a retrospective cohort study of patients diagnosed with advanced SBA at a single tertiary center in Thailand between 2005 and 2024. The patients were treated with palliative systemic chemotherapy or best supportive care (BSC). Survival outcomes were assessed using Kaplan–Meier estimates and Cox regression analyses. Propensity score-matching (PSM) was performed to adjust for baseline imbalances. Results: This study included 106 patients; of these, 39 (36.8%) received palliative chemotherapy. After 1:1 PSM, 39 matched pairs were analyzed. Chemotherapy significantly improved overall survival (OS) compared with that of the BSC, with a median OS of 10.4 vs 2.6 months (hazard ratio 0.36; 95% confidence intervals 0.22–0.59; P <0.001). Among chemotherapy-treated patients, the median progression-free survival was 5.95 months, and the objective response rate was 10.3% overall, increasing to 21.1% among evaluable patients receiving doublet regimens. Multivariate analysis revealed that poor Eastern Cooperative Oncology Group performance status (≥2), poorly differentiated histology, and duodenal tumor location independently predicted worse OS. Conclusion: Palliative chemotherapy significantly prolongs survival in patients with advanced SBA compared with that of BSC, particularly in those with a good performance status. Doublet fluoropyrimidine-based regimens offered superior outcomes. These findings support the use of systemic chemotherapy for this rare malignancy, highlighting the significance of patient selection and performance status in guiding treatment decisions.