目的： 探讨辅助化疗在不同分期的十二指肠腺癌（DAC）病人中的有效性。方法： 研究对2000年1月至2021年12月之间在SEER数据库中诊断为DAC的病人进行回顾性分析。使用Kaplan-Meier曲线分析辅助化疗对不同分期DAC生存率的影响。采用单因素和多因素COX回归分析确定辅助化疗是否为影响癌症特异生存（CSS）和总生存（OS）的独立预后因素。结果： 共有1 195例符合纳入标准的病人纳入研究。其中，620例（51.9%）术后接受辅助化疗，定义为辅助化疗组，575例（48.1%）仅接受手术，定义为其他组。经倾向性评分匹配后，共634例纳入后续分析。亚组分析表明，ⅢA期和ⅢB期辅助化疗组与其他组病人CSS和OS差异有统计学意义（P<0.05），Ⅰ期、ⅡA期、ⅡB期辅助化疗组与其他组病人CSS和OS差异均无统计学意义（P>0.05）。多因素分析表明，辅助化疗是影响DAC病人CSS和OS的独立保护因素。此外，年龄、诊断年份、肿瘤分级、区域淋巴结检出数（RNE）、TNM分期也是CSS和OS的独立保护或危险因素（P<0.05）。结论： 根据分期分层分析，DAC病人辅助化疗的生存获益如下：ⅢA和ⅢB期的病人CSS和OS均获益，Ⅰ、ⅡA、ⅡB期病人CSS或OS均无法获益。

Objective To investigate the efficacy of adjuvant chemotherapy for patients with duodenal adenocarcinoma (DAC) at different stages. Methods A retrospective analysis was performed on patients diagnosed with DAC between January 2000 and December 2021 using data from the SEER database. Kaplan-Meier curves were utilized to evaluate the impact of adjuvant chemotherapy on survival outcomes in DAC patients with different stages. Univariate and multivariate COX regression analyses were performed to determine whether adjuvant chemotherapy served as an independent prognostic factor for cancer-specific survival (CSS) and overall survival (OS). Results A total of 1 195 patients meeting the inclusion criteria were included in the study. Of these, 620 patients (51.9%) received adjuvant chemotherapy after surgery were defined as the adjuvant chemotherapy group, whereas 575 patients (48.1%) underwent surgery alone were defined as the other group. After propensity score matching, 634 patients were retained for subsequent analysis. Subgroup analysis demonstrated that there were statistically significant differences in CSS and OS between the adjuvant chemotherapy group and other group for stage ⅢA and ⅢB patients (P < 0.05), while no statistically significant differences in CSS and OS between the adjuvant chemotherapy group and other group for stageⅠ, stageⅡA, stage ⅡB patients (P > 0.05). Multivariate analysis identified adjuvant chemotherapy as an independent protective factor for both CSS and OS in DAC patients. Additionally, age, year of diagnosis, tumor grade, number of regional lymph nodes examined (RNE), and TNM stage were identified as independent protective or risk factors for CSS and OS (all P < 0.05). Conclusions Based on substage stratification, the survival benefits of adjuvant chemotherapy for DAC patients are as follows: patients with stage ⅢA and ⅢB benefit in both CSS and OS, while patients with stage Ⅰ, Ⅱ A, and ⅡB do not benefit in either CSS or OS.