Perineural Invasion and Lymph Node Involvement as Indicators of Surgical Outcome and Pattern of Recurrence in the Setting of Preoperative Gemcitabine-Based Chemoradiation Therapy for Resectable Pancreatic Cancer

Abstract

To analyze the histopathological indicators significantly associated with surgical outcome and the pattern of recurrence in the setting of preoperative gemcitabine-based chemoradiation therapy (CRT) and subsequent pancreatectomy. Clinicopathological assessment of the resected specimen is an indispensable tool for predicting patient prognosis and localizing high-risk sites for tumor relapse. This procedure is also essential for the establishment of efficient postoperative follow-up protocols in the setting of a preoperative CRT strategy. In a prospective phase II clinical trial at our hospital, 110 patients received preoperative CRT and subsequent resection. All 110 resected cases were included in this study. We employed disease-free survival (DFS) as a surgical outcome, and the pattern of recurrence was divided into 2 categories: (1) recurrence in the abdominal cavity (RAC), defined as either a locoregional or a peritoneal recurrence; or (2) distant recurrence (DR), defined as cancer recurrence in a distant organ. Clinicopathological variables were analyzed in association with DFS, RAC, and DR. Positive nodal involvement and perineural invasion were independent factors that were significantly associated with an unfavorable DFS (P = 0.021 and P = 0.026, respectively). The presence of perineural invasion was the single independent variable significantly associated with an increased risk of RAC (P = 0.002), whereas the status of nodal involvement was the single independent variable significantly associated with an increased risk of DR (P = 0.013). The status of nodal involvement and perineural invasion in resected specimens are significantly associated with DFS and clearly predict the pattern of recurrence in the setting of a preoperative gemcitabine-based CRT strategy. This study is registered at UMIN-CTR and carries the ID number UMIN000001804.