Prognostic impact of pancreatic intraepithelial neoplasia at the resection margin in pancreas cancer

During pancreatic ductal adenocarcinoma (PDAC) resection, it is essential to secure a negative surgical margin for cancer cells. However, the prognostic impact of pancreatic intraepithelial neoplasia (PanIN) at the resection margin remains unclear. Patients with PDAC who underwent pancreatectomy at our institution were retrospectively analyzed. Based on the pathological diagnosis of the pancreatic resection margin, the patients were classified into three groups: cancer-negative (Neg), low-grade PanIN (LG-PanIN), and cancer-positive (Pos). The postoperative prognoses between the groups were compared. Prognostic factors were compared using the Cox regression analysis. Of the 101 patients, the numbers per margin category were as follows: Neg, n=74; LG-PanIN, n=18; and Pos, n=9. Regarding disease-specific survival (DSS) or recurrence-free survival (RFS), the LG-PanIN group had the best prognosis, while the Pos group had the worst. Multivariate cox regression analysis showed that being positive for peritoneal lavage cytology was the independent poor prognostic factor for DSS (hazard ratio, 2.42 [95% confidence interval {CI}, 1.01–5.80]; P=0.047). The microscopically poorly differentiated type had poorer DSS (P=0.049) and RFS (P=0.031) prognoses than did the others. In our hypothesis generating study for observational cohort, the presence of LG-PanIN at the resection margin did not negatively affect the prognosis. Although the results cannot imply the direct surgical recommendations, it would affect to determine whether additional resection of pancreatic margin should be performed during surgery.