Preoperative radiotherapy improves overall survival of pT4 pancreatic ductal adenocarcinoma patients after surgical resection

Abstract

Purpose: Aim of delivering radiotherapy for pancreatic ductal adenocarcinoma (PDAC) patients was to sterilize vessel margin, increase R0 resection rate, and delay local progression. Whether preoperative radiotherapy (PR) could prolong overall survival (OS) of surgical candidates remained unknown. Methods: PDAC patients receiving radical resection from surveillance, epidemiology, and end results (SEER) database were enrolled. Propensity score matching (PSM) was conducted to balance difference in baseline characteristics and survival analyses was performed to compared OS between PR and upfront resection (UR) groups. Cox proportional hazards regression model and subgroup analyses were utilized to identify prognostic factors. Results: 11,665 and 597 PDAC patients receiving UR and PR followed by resection from 2004 to 2016 were identified respectively, while baseline characteristics were distinct between groups. After PSM, PR was not associated with better OS (UR vs PR, 26 vs 27 months). Subgroup analyses showed that PR was a protective factor in pT4 (hazard ratio (HR) = 0.64, 95% confidence interval (CI): 0.47-0.88) but a negative predictor in pT1 (HR = 1.79, 95% CI: 1.08-2.97) patient populations. Survival analyses showed that PR improved OS of patients with pT4 stage (UR vs PR, 19 vs 25 months) and involvement of celiac axis (CA), superior mesenteric artery (SMA), and aorta (UR vs PR, 20 vs 27 months), while PR was associated with worse OS in patients with pT1 tumor (UR vs PR, 39 vs 24 months). Conclusion: PR could improve survival of resected PDAC patients with pT4 stage or with CA, SMA, and aorta invasion.