Pathologic tumor response to neoadjuvant therapy in borderline resectable pancreatic cancer

Background: Previous studies have demonstrated the prognostic significance of pathologic tumor response in pancreatic adenocarcinoma following neoadjuvant therapy（NAT）. The aim of this study was to determine the incidence of significant pathologic response to NAT in borderline resectable pancreatic cancer（BRPC）, and association of NAT regimen and other clinico-pathologic characteristics with pathologic response. Methods: Patients with BRPC who underwent NAT and pancreatic resection between January 2012 and June 2017 were included. Pathologic response was assessed on a qualitative scale based on the College of American Pathologists grading system. Demographics and baseline characteristics, oncologic treatment, pathology, and survival outcomes were compared. Results: Seventy-one patients were included for analysis. Four patients had complete pathologic responses（tumor regression score 0）, 12 patients had marked responses（score 1）, 42 had moderate responses（score 2）, and 13 had minimal responses（score 3）. Patients with complete or marked responses were more likely to have received neoadjuvant gemcitabine chemoradiation（62.5%, 38.1%, and 23.1% of the complete/marked, moderate, and minimal response groups, respectively; P = 0.04）. Of the complete/marked, moderate, and minimal response groups, margins were negative in 75.0%, 78.6%, and 46.2%（ P = 0.16）; node negative disease was observed in 87.5%, 54.8%, and 15.4%（ P ＜ 0.01）; and median overall survival was 50.0 months, 31.7 months, and 23.2 months（ P = 0.563）. Of the four patients with pathologic complete responses, three were disease-free at 66.1, 41.7 and 31.4 months, and one was deceased with metastatic liver disease at 16.9 months. Conclusions: A more pronounced pathologic tumor response to NAT in BRPC is correlated with node negative disease, but was not associated with a statistically significant survival benefit in this study.