The influence of adjuvant radiotherapy dose on overall survival in patients with resected pancreatic adenocarcinoma.

BACKGROUND: Adjuvant radiotherapy (A-RT) for patients with resected pancreatic adenocarcinoma (PAC) is controversial. In the current study, the authors aim to determine whether there is an association between overall survival (OS) and A-RT dose.
METHODS: National Cancer Data Base (NCDB) data were obtained for all patients who received A-RT for resected PAC from 1998 through 2002. Univariate and multivariate survival analyses were performed along with Kaplan-Meier estimates for A-RT levels < 40 grays (Gy), 40 Gy to < 50 Gy, 50 Gy to < 55 Gy, and ≥ 55 Gy.
RESULTS: A total of 1385 patients met the inclusion criteria. The median age of the patients was 64 years (range, 29 years-87 years). All patients underwent surgical resection and A-RT with or without chemotherapy. A total of 231 patients were diagnosed with stage I disease, 273 were diagnosed with stage II disease, 734 were diagnosed with stage III disease, and 126 were diagnosed with stage IVA disease (according to the fifth edition of the American Joint Committee on Cancer); 21 were found to have an unknown stage of disease. The median A-RT dose was 45 Gy (range, 1.63 Gy-69 Gy). The median OS was 21 months (95% confidence interval [95% CI], 19 months-23 months). On multivariate analysis, an A-RT dose < 40 Gy (hazards ratio [HR], 1.30 [95% CI, 1.03-1.66]; P = .031), an A-RT dose of 40 Gy to < 50 Gy (HR, 1.17 [95% CI, 1.00-1.37]; P = .05), and an A-RT dose ≥ 55 Gy (HR, 1.44 [95% CI, 1.08-1.93]; P = .013) predicted worse OS compared with the reference category of 50 Gy to < 55 Gy.
CONCLUSIONS: A-RT doses of < 40 Gy, 40 Gy to < 50 Gy, and ≥ 55 Gy were found to be associated with an inferior OS. The dose of A-RT delivered appears to influence OS and a prospective study evaluating the addition of optimally delivered A-RT for patients with resected PAC is needed.