Immunohistological evaluation of mismatch repair deficiency in pancreatic ductal adenocarcinoma treated with surgical resection

Abstract

Background The frequency and prognosis of resected deficient mismatch repair (dMMR) pancreatic ductal adenocarcinoma (PDAC) remain unclear. This study was designed to assess the frequency of dMMR and its clinicopathological relevance in Japanese patients with PDAC treated with surgical resection. Methods A total of 400 consecutive patients with PDAC who underwent surgical resection at Hiroshima University were enrolled. Immunohistochemical staining with four antibodies including MLH1, MSH2, MSH6, and PMS2 was used to determine the presence of dMMR in PDAC specimens. Statistical analyses were applied to evaluate the frequency and clinical outcomes of these patients. Results Of these 400 patients, five (1.3%) had dMMR (two had MLH1 deficiency, two had PMS2 deficiency, and one had MSH2 deficiency). We found a significantly different histological differentiation pattern between patients with dMMR and those with proficient mismatch repair (pMMR) (P = .03). Univariate survival analysis revealed no significant differences between dMMR and pMMR in recurrence-free survival (P = .268) or overall survival (P = .173). Conclusions The incidence of dMMR in Japanese patients with resected PDAC is low, and we found no ethnic-specific differences when comparing the incidence to that in Caucasian patients. In the current study, no significant difference was found in recurrence-free and overall survival between patients with dMMR and pMMR.