Use of Radiation Therapy in Locally Advanced Pancreatic Cancer Improves Survival: A SEER Database Analysis

Although both radiation therapy and chemotherapy are frequently used to treat locally advanced pancreatic cancer (LAPC) patients, the role of radiation therapy remains controversial with data evaluating its efficacy mostly derived from small randomized trials. In this study, we evaluate the survival benefit of radiation therapy using SEER dataset in patients with LAPC.

The SEER Registry dataset from 2004 to 2011 was queried to identify LAPC (TNM stage III) patients. Patients with survival <2 months, unknown radiation status, or who received postoperative radiation were excluded. Multivariate analyses of prognostic factors related to survival were performed using a Cox proportional hazard-regression model. Propensity scores were estimated using probit regression.

Our search identified 4460 patients; 59% who received radiation and 41% who did not. Radiation group patients were younger (below 65 y old: 49% vs. 38%), had smaller tumor size (largest dimension <4.5 cm: 80% vs. 75%), less lymph node involvement (33% vs. 36%), and lower rate of surgical resection (4% vs. 9%). Patients who received radiation therapy had better survival (HR=0.773; 95% CI, 0.687-0.782). The 12-month overall survival in the radiation group and nonradiation group was 43% versus 29%, respectively (P<0.001). On multivariate analyses, radiation was independently associated with improved outcomes. The survival benefit with radiation was observed in propensity score-matched cohort.

Radiation therapy was associated with improved survival. Prospective randomized trials are needed to confirm these findings. The optimal schedule and radiation type remain undetermined.