(P100) Radiation Therapy Is Associated With Improved Survival In Patients With Localized Pancreatic Cancer S/P Whipple Procedure Without Increased Morbidity: Results of a Study from the Surveillance, Epidemiology, and End Results (SEER) Registry Data

Weisi Yan, MD, Julia Manzerova, MD, PhD, Jason C. Ye, MD, Paul Christos, DrPH, MS, Dattatreyudu Nori, MD, MBBS, Kun-San C. Chao, MD, Akkamma Ravi, MD, MBBS; New York Hospital Queens; New York Presbyterian Hospital; Weill Cornell Medical College

Background: Patients with localized pancreatic cancer tend to receive chemotherapy after surgery. However, the role of radiation therapy (RT) in resectable pancreatic cancer is still debated. For the current study, we evaluated the effect of adjuvant RT on survival as well as treatment-related toxicity in patients with localized pancreatic cancer who underwent Whipple procedure (pancreaticoduodenectomy).

Methods: The analysis included 3,721 patients reported to the Surveillance, Epidemiology, and End Results (SEER) registry of the National Cancer Institute from 2003 to 2010 who had localized pancreatic cancer and underwent a cancer-directed Whipple procedure (pancreaticoduodenectomy). Cause-specific survival (CSS) was evaluated by Kaplan-Meier survival analysis, and the log-rank test was used to compare CSS between treatment categories of interest. Multivariable Cox regression model analysis was used to elucidate the factors that contribute to pancreatic cancer death. Adjusted hazard ratios (AHRs) and 95% confidence intervals (95% CIs) were calculated for risk of pancreatic cancer-related death. Deaths due to RT were also studied.

Results: Of the 3,721 patients, 1,520 (40.8%) received RT. Median follow-up time (based on survivors) was 17 months (range: 0.10–83.0 mo). CSS improved significantly in patients who received RT, with a median survival of 21.0 months (95% CI, 19.8–22.2 mo) compared with 17 months (95% CI, 15.8–18.2 mo) for patients who did not receive RT (P < .0001). On multivariable analysis, age > 65 years, T-stage, N-stage, and grade were associated with increased risk of pancreatic-specific death (P < .05 for all factors). Out of 1,520 cases, 4 (0.2%) patients died of radiation treatment effects; out of a total of 2,201 cases, 6 (0.2%) patients died of surgery and/or chemotherapy treatment effects.

Conclusions: Adjuvant RT following Whipple procedure was associated with improved CSS compared with cancer-directed surgery alone without radiation in patients with localized pancreatic cancer. Old age, white race, higher T- and N-stage, and grade were associated with worse outcome. Morbidity was not increased with adjuvant RT.