Role of Adjuvant Radiotherapy in Left-Sided Pancreatic Cancer-Population-Based Analysis with Propensity Score Matching.

This population-based study evaluated the survival impact of postoperative radiotherapy (PORT) in left-sided pancreatic cancer. The Surveillance, Epidemiology, and End Results (SEER) database was used to identify patients with surgically resected left-sided pancreatic adenocarcinoma from 2004 to 2010. Propensity score matching was conducted to compare PORT and non-PORT groups. A total of 445 patients were identified, and PORT was performed in 180 (40 %) patients. In the unmatched population, there were no significant differences in overall survival (OS) (P = 0.197) and cause-specific survival (CSS) (P = 0.379) between the PORT and non-PORT groups. After propensity score matching, the patients treated with PORT had longer median OS (P = 0.012) and CSS (P = 0.039) than the non-PORT group. In propensity-adjusted multivariate analysis, non-receipt of PORT was a poor prognostic factor in OS (hazard ratio [HR] 1.39, 95 % confidence interval [CI] 1.08-1.79), and CSS (HR 1.31, 95 % CI 1.01-1.71). The log odds of positive lymph nodes (LOODS) (≥-0.73) was also associated with worse OS (P = 0.003) and CSS (P = 0.001). In left-sided pancreatic cancer, considering the addition of PORT is a reasonable option as in pancreatic head cancer. The LOODS was suggested as a strong predictive indicator of the patients' prognoses.