Radiation as a single modality treatment in localized pancreatic cancer.

Abstract

703 Background: Locally advanced pancreatic cancer (LAPC) is managed with multimodality therapy. A subset of patients with LAPC are not good candidates for aggressive treatment. The aim here is to evaluate the outcomes of single modality radiation therapy for LAPC using the National Cancer Database (NCDB). Methods: Data was obtained between years 2004 and 2013. Pancreatic ductal adenocarcinoma (PDAC) patients with unresectable local disease were identified excluding patients who received chemotherapy or surgery. Univariate and multivariable analyses identified factors associated with patient outcome. Kaplan-Meier analysis and Cox proportional hazards models were used for patient characteristics and overall survival (OS). Results: A total of 6,590 patients were included; 480 (6.9%) received radiation therapy only and 6470 (93.1%) received no treatment. Mean age was 73.5 (range, 28‐90) years, with the majority being White (N = 5685; 83.2%) and female (N = 3779; 54.4%). Poorly differentiated histology and tumors ≥ 4 cm ( > T3 stage) accounted for 47.8% and 52.7%, respectively. The median dose of radiation was 39.6 Gy. Stereotactic body radiation (SBRT) was given in 64 patients and external-beam/Intensity modulated radiotherapy (IMRT) in 416 patients. Charlson-Deyo score of +1 was seen in 34.4% of patients who received no treatment, 32.8% of patients who received SBRT and in 29.8% of patients who received external-beam IMRT. Radiation therapy was associated with improved OS compared to no treatment in univariate and multivariable analyses controlling for sex, Charlson-Deyo score, age, tumor size, amongst other covariates. Median OS for patients who received SBRT, external-beam/IMRT or no radiation was 8.6, 6.7 and 3.4 months; respectively (P < 0.001). There is a significant difference in 12-month OS for the SBRT cohort (31.9%; 95% CI 20.9%-43.5%) compared to patients who received no radiation (15.1%; 95% CI 14.2%-16.0%), similarly seen on multivariable analysis (HR 0.50; 95% CI 0.38-0.65; P < 0.001). Conclusions: The current study is the first to evaluate the efficacy of radiation as single modality therapy in LAPC. The results suggest a potential benefit for radiation therapy alone, in comparison to no treatment.