The benefit of combining postoperative radiation therapy (PORT) with chemotherapy for resected patients with pancreatic adenocarcinoma is controversial. We sought to determine the effects of PORT on survival in patients with pancreatic adenocarcinoma who underwent primary site surgery. Patients with pancreatic adenocarcinoma receiving primary tumor surgery between 1988 and 2012 were identified from the Surveillance, Epidemiology and End Results (SEER) database. We estimated the association between PORT and other clinicopathologic factors and survival. In total, 5304 patients were identified who underwent pancreatic resection including 2093 patients who had PORT and 3211 patients who had no PORT. Median overall, cancer-specific, and other-cause survival were 19.0, 20.0, and 196.0 months, respectively, with PORT versus 14.0, 15.0, and 163.0 months, respectively, without PORT (all P < 0.001). Subset analysis revealed that the benefit of PORT was limited to patients with N1 disease. Median overall, cancer-specific, and other-cause survival for patients with N1 disease were 18.0, 18.0, and NA months, respectively, with PORT versus 12.0, 13.0, and 154.0 months, respectively, without PORT (all P < 0.001). Regardless the number of positive lymph node count (PLN) and lymph node ratio (LNR), PORT was always associated with increased survival on multivariate analysis in patients with N1 disease (all P < 0.001). In summary, survival benefits might be obtained from PORT on lymph node positive patients with pancreatic adenocarcinoma.
Keywords: lymph node metastasis; pancreatic adenocarcinoma; postoperative radiation therapy; survival.