Clinical significance and predictors of complete or near-complete histological response to preoperative chemoradiotherapy in patients with localized pancreatic ductal adenocarcinoma.

Abstract Background The clinical value and predictors of a favorable histological response to preoperative chemoradiotherapy (CRT) in pancreatic ductal adenocarcinoma (PDAC) remains undefined. Objective To assess the significance and predictors of a favorable histological response to preoperative CRT in patients with localized PDAC. Methods The study included 203 patients with localized PDAC undergoing curative-intent resection after CRT. The rate of R0 resection and overall survival (OS) and recurrence-free survival (RFS) were correlated with the grading of histological response to determine optimal stratification. Clinical factors associated with a significant histological response were evaluated using multivariate regression analysis. Results Among all patients, eight patients (3.9%) had a grade 4 (pCR); 40 (19.4%) had a grade 3 estimated rate of residual neoplastic cells Conclusions pCR or near-pCR to preoperative CRT contributed to achieving a high rate of R0 resection and improving survival for localized PDAC. The use of gemcitabine plus S-1 as a radiosensitizer, lower serum CA19-9 level after CRT, and longer preoperative treatment duration were significantly associated with pCR or near-pCR.