Abstract
BACKGROUND: Duodenal adenocarcinoma (DAC), the most common subtype of small bowel adenocarcinoma, is rare. As a result, the survival benefit of adjuvant chemotherapy (AC) for patients with DAC following surgical resection remains controversial and poorly defined. This study aimed to evaluate the association between AC and survival and to identify patient subgroups that derive the greatest benefit. METHODS: A retrospective analysis was conducted using data from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2021). Patients with DAC who underwent surgical resection were included and divided into AC and no-AC groups. Overall survival (OS) and cancer-specific survival (CSS) were compared. Propensity score matching (PSM) was employed as a sensitivity analysis to minimize confounding. Subgroup interaction analyses were performed to identify differential treatment effects. RESULTS: Of 3,296 patients, 704 (21.4%) received AC. In the analysis of the entire cohort, AC was independently associated with improved OS [hazard ratio (HR) =0.63, 95% confidence interval (CI): 0.53-0.74, P<0.001] and CSS (HR =0.67, 95% CI: 0.55-0.82, P<0.001). This benefit was robustly confirmed in the PSM-matched cohort of 878 patients. Subgroup analyses revealed significant interactions, indicating that the survival benefit was most pronounced in patients aged ≥65 years and those with lymph node metastasis (N1/N2) or advanced T-stage (T3/T4). CONCLUSIONS: This large, population-based study provides robust evidence that AC is associated with significantly improved survival after surgery for DAC, particularly in older patients and those with lymph node-positive or locally advanced disease. These findings support the use of AC to enhance survival outcomes in specific DAC patient groups.