Survival benefits from postoperative radiation therapy on lymph node positive patients with pancreatic adenocarcinoma

// Zuguang Xia 1, * , Xiaoyan Jia 3, * , Kai Chen 2 , Dapeng Li 2 , Jing Xie 2 , Hong Xu 2 , Yixiang Mao 2, 3 1 Department of Medical Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China 2 Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, China 3 Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA * These authors contributed equally to this work Correspondence to: Zuguang Xia, email: zuguang_xia@163.com Hong Xu, email: 13301549066@163.com Yixiang Mao, email: maoyix@gmail.com Keywords: pancreatic adenocarcinoma, postoperative radiation therapy, lymph node metastasis, survival Received: March 10, 2016      Accepted: April 16, 2016      Published: May 26, 2016 ABSTRACT 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.