Adjuvant therapy for margin positive pancreatic cancer.

Abstract

390 Background: Pancreatic cancer continues to have a dismal prognosis despite improvements in surgical care. Approximately 26% of patients are deemed resectable, and at the time of operation, 28% will have R1 resections. Adjuvant chemotherapy (AC) or chemoradiation (CRT) is recommended, however the magnitude of benefit is unclear. We sought to examine the impact these therapies on R1 resected pancreatic cancer. Methods: Utilizing the National Cancer Database we identified patients who underwent pancreatic resection for adenocarcinoma. Patients were stratified by resection status and adjuvant therapy. Baseline comparisons of patient characteristics were made using Mann-Whitney U, Kruskal Wallis and Pearson’s Chi-square test as appropriate. Survival analyses were performed using the Kaplan-Meier method. Multivariable cox proportional models(MVA) were developed to identify predictors of survival. All statistical tests were two-sided and α <0.05 was considered significant. Results: We identified 28,440 patients: 22,005 (77.4%) underwent R0 resections and 6,435 (22.4%) underwent R1 resections with a median age of 67.5 years (18-90) and median tumor size of 3.1 cm (2.4-4.2). Patients with tumor size >2cm were more likely to undergo R1 resections, p<0.001. Within the R1 resection group, AC was administered in 1,802 (19.4%), CRT 2,153 (28.5%), and no adjuvant therapy (NA) 2,480 (21.4%). Adjuvant therapy improved survival in all patients with median and 5-year survival of: AC (21.7 months, 17.45%), CRT (23.3 months, 20.9%) vs NA (19.5 months, 19.1%), p<0.001. In the R1 resection cohort survival was also improved with adjuvant therapy with CRT demonstrating the most significant improvement: AC (15.9 months, 6.5%), CRT (18.7 months. 11.2%) vs NA (12.5 months, 8.7%), p<0.001. Additionally CRT but not AC improved survival in the R1 node negative, p<0.004, and node positive, p<0.001. AC benefited survival in R1 node positive patients, p<0.001. MVA revealed age, tumor grade, tumor size >2cm, T-stage, N-stage, AC, and CRT were predictive of survival. Conclusions: Patients with pancreatic cancer who undergo R1 resection have significant improvement in survival when treated with adjuvant CRT and AC. However, benefits were greater in those receiving adjuvant CRT.