Which Factors Are Associated with Positive Resection Margin in Pancreatic Ductal Adenocarcinoma for different surgical procedures? Results Based on a Standard Pathological Evaluation System-Retrospective Cohort Study

Background/Objectives: The present study identified the independent risk factors of R1 resection in pancreaticoduodenectomy (PD) and distal pancreatosplenectomy (DP) for patients with pancreatic ductal adenocarcinoma (PDAC).Methods：Consecutive patients who were operated from 1st December 2017 to 30th December 2018 with curative intent were analyzed retrospectively. A standardized pathological examination with digital whole-mount slide images (DWMSIs) was utilized for the resection margin status. R1 was defined as microscopic tumor infiltration within 1 mm to the resection margin. The potential risk factors of R1 resection for PD and DP were analyzed separately by univariate and multivariate logistic regression analyses. Results：For the 240 patients who underwent PD, and the 146 patients who underwent DP, the R1 resection rates were 30.8% and 35.6 %, respectively. Univariate analysis on risk factors of R1 resection for PD were tumor location, absence of tumor necrosis, N staging, and TNM staging; while those for DP were perineural invasion, T staging, and TNM staging. Multivariate logistic regression analysis showed the location of tumor in the neck and uncinate process, and N1/2 staging were independent risk factors of R1 resection for PD; while those for DP were T3/4 staging. Conclusions：The clarification of the risk factors of R1 resection might clearly make surgeons take better decisions on surgical strategies for different surgical precedures in patients with PDAC.