Survival benefit with adjuvant radiation therapy in surgically resected pancreatic cancer

Greco JA, Castaldo ET, Feurer ID, Pinson CW, Chakravarthy AB, Merchant NB, Parikh AA.

2007 Gastrointestinal Cancers Symposium; Abstract No: 109.

Introduction: Survival for patients with pancreatic cancer remains abysmal. Early studies have shown a benefit of adjuvant chemoradiation therapy after surgical resection. However, recent trials have shown a benefit of adjuvant chemotherapy while showing a negative effect with the addition of radiation therapy. This has led to significant controversy about the role of adjuvant radiation therapy (XRT) in these patients. The primary aim of this population-based study, therefore, is to determine if adjuvant XRT improves overall survival in patients with resected pancreatic cancer. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) registry, all patient records from 1973-2003 with surgically resected pancreatic adenocarcinoma were queried. Patients with Stage 3 or 4 disease, preoperative or intraoperative radiation therapy, multiple primary malignancies, or incomplete tumor grading, staging, radiation, or demographic data were excluded. Kaplan-Meier methods and the log-rank test were used for survival data. A Cox regression model was tested with gender, race, tumor grade, age over 60 years, stage, and radiation as co-variates. Results: The analysis included 2,636 patients with resected pancreatic cancer (1,123 received adjuvant XRT and 1,513 did not). With a mean f/u of 19 mos, median overall survival for the patients receiving XRT was 18 mos compared to 11 mos for the group that did not (p<0.01). Additionally, Cox regression demonstrated that patients who received adjuvant XRT had a statistically significant increase in overall survival when compared to patients who received no adjuvant XRT (HR = 0.57; 95% CI 0.52 - 0.63; p<0.01). Independent significant factors leading to decreased survival included race other than black compared to white (p<0.01), moderately (p<0.01) and poorly differentiated (p<0.01) histology, age greater than 60 yrs (p<0.01) and increased stage of tumor (p<0.01). Conclusions: These data suggest a survival benefit for the addition of radiation therapy following surgical resection of pancreatic adenocarcinoma. Radiation therapy was an independent predictor of survival in this model after adjusting for the effects of gender, race, tumor grade, age and stage.