Adjuvant radiotherapy for pancreatic cancer is associated with a survival benefit primarily in stage IIB patients

Abstract

The role of adjuvant radiotherapy (RT) for pancreatic cancer remains controversial despite the completion of three multi-institutional randomized trials. This study examines the survival impact of postoperative RT in a large population-based database. Patients with pancreatic cancer diagnosed from 1988 to 2003 were identified in the Surveillance, Epidemiology, and End Results (SEER) database. The cohort was limited to patients who underwent resection of nonmetastatic disease to yield a population of 3252 patients. The primary end point was overall survival. Survival analyses were conducted using corrections for perioperative mortality as well as a propensity score analysis to account for baseline differences in patient characteristics. Multiple independent factors were associated with RT use, including patient age and disease stage (P < 0.0001). In general, younger patients and those with more advanced disease were more likely to receive RT. Disease stage significantly affected survival (P < 0.0001). For patients who survived at least 6 months, adjuvant RT was associated with increased survival [hazard ratio (HR), 0.87; 95% confidence interval (CI), 0.80-0.96]. On subgroup analysis, only stage IIB (T1-3N1) patients enjoyed a statistically significant benefit associated with RT (HR, 0.70; 95% CI, 0.62-0.79). Adjuvant RT is frequently given to patients in the United States after resection of their pancreatic cancer. Although RT is associated with a survival benefit for nonmetastatic patients as a whole, this trend appears to predominantly derive from a survival benefit in patients with stage IIB disease.