Whether early stage pancreatic ductal adenocarcinoma patients could benefit from the post-operation chemotherapy regimens: a SEER-based propensity score matching study

To investigate whether chemotherapy could prolong the postoperative survival time in patients with early stages pancreatic ductal adenocarcinoma (PDAC). A total of 5280 stage ⅠA -ⅡB PDAC patients diagnosed from 2010 to 2015 were selected from surveillance，epidemiology，and end results (SEER) database. Propensity score matching (PSM) analysis was adopted to reduce the baseline differences between the groups. Univariate survival analysis was conducted with the Kaplan-Meier method. Multivariate survival analysis was performed with the Cox proportional hazards model. Univariate and multivariate survival analyses showed that age, differentiation, stage, chemotherapy were independent risk factors for the survival of PDAC patients. After PSM, it is found that adjuvant chemotherapy could prolong the median overall survival time (mOS) for stage ⅠB, ⅡA and ⅡB patients. However, for stage ⅠA patients, there were no significant differences in 3-year survival rate and mOS between patients with chemotherapy (=283) and without chemotherapy (=229) (57.4% vs 55.6%, vs all >0.05). Further analyses show that among 101 patients with well differentiated PDAC and 294 patients with moderately differentiated PDAC, there were no significant differences in survival rate and mOS between patients with and without chemotherapy (all >0.05). Among 117 patients with low-differentiated + undifferentiated PDAC, 3-year survival rate and mOS in patients with chemotherapy were significantly better than those without chemotherapy (48.5% vs 34.1%, vs all <0.05). Chemotherapy regimen used currently is not beneficial for patients with moderately and well differentiated stage ⅠA PDAC, but it is an independent prognostic factor for low-differentiated + undifferentiated PDAC patients.