Analysis of radiotherapy impact on survival in resected stage I/II pancreatic cancer patients: a population-based study

BACKGROUND: The application of radiotherapy (RT) in pancreatic cancer remains controversial. AIM: The aim of the study was to evaluate the efficacy of radiotherapy (neoadjuvant and adjuvant radiotherapy) for resectable I/II pancreatic cancer. METHODS: Fourteen thousand nine hundred seventy-seven patients with pancreatic cancer were identified from SEER database from 2004 to 2015. Multivariate analyses were performed to determine factors including RT on overall survival. Overall survival and overall mortality among the different groups were evaluated using the Kaplan-Meier method and Gray’s test. RESULTS: Patients were divided into groups according to whether they received radiotherapy or not. The median survival time of all 14,977 patients without RT was 20 months, neoadjuvant RT was 24 months and adjuvant RT was 23 months (p < 0.0001). Median survival time of 2089 stage I patients without RT was 56 months, significantly longer than those with RT regardless of neoadjuvant or adjuvant RT (no RT: 56 months vs adjuvant RT: 37 months vs neoadjuvant RT: 27 months, P = 0.0039). Median survival time of 12,888 stage II patients with neoadjuvant RT was 24 months, adjuvant RT 22 months, significantly prolonged than those without radiotherapy (neoadjuvant RT: 24 months vs adjuvant RT: 22 months vs no RT: 17 months, P<0.0001). Neoadjuvant RT (HR = 1.434, P = 0.023, 95% CI: 1.051–1.957) was independent risk factors for prognosis of stage I patients, and adjuvant RT (HR = 0.904, P < 0.001, 95% CI: 0.861–0.950) predicted better outcomes for prognosis of stage II patients by multivariate analysis. The risk of cancer-related death caused by neoadjuvant RT in stage I and no-RT in stage II patients were significantly higher. CONCLUSIONS: The study identified a significant survival advantage for the use of adjuvant RT over surgery alone or neoadjuvant RT in treating stage II pancreatic cancer. RT was not associated with survival benifit in stage I patients.