Germline DNA damage repair gene mutations in pancreatic cancer patients with personal/family histories of pancreas/breast/ovarian/prostate cancer in a Japanese population

Abstract Aim Cancer patients with personal/family histories of pancreatic/breast/ovarian/prostate cancer are associated with a higher likelihood of harboring DNA damage repair (DDR)‐related germline mutations. Here, we aimed to obtain a better understanding of DDR‐related germline mutations in Japanese pancreatic ductal adenocarcinoma (PDAC) patients with personal and/or family histories of BRCA‐related cancers of the pancreas, breast, ovary, and prostate. Methods We performed next‐generation sequencing (NGS) and evaluated germline mutations in nine DDR‐related genes (BRCA1, BRCA2, ATM, PALB2, CHEK2, MLH1, MSH2, MSH6, and PMS2) in PDAC patients with personal and/or family histories. Results Of 196 patients with PDAC, 39 (19.9%) fulfilled the criteria for at least one family history of pancreatic/breast/ovarian/prostate cancer in first‐degree relatives (sibling–sibling or parent‐child) or the personal history of these malignancies. Targeted NGS revealed that four (10.2%) of 39 patients with personal/family histories harbored deleterious germline mutations—two in BRCA2, one in ATM, and one in MLH1. Both the BRCA2 variants showed frameshift mutations due to short insertion/deletions. In the 39 patients undergoing NGS, a similar distribution of the clinicopathological characteristics was observed between those with deleterious mutations/variants of unknown significance (VUSs) and with benign/wild types. Patients with deleterious germline mutations/VUSs in DDR‐related genes showed a significantly more favorable prognosis than those with benign mutations/wild‐type genes (hazard ratio: 0.160, P = .040). Conclusions A significant fraction of PDAC patients with personal/family histories of BRCA‐related cancers harbored deleterious germline mutations in DDR‐related genes. DDR‐related germline gene mutations might be a favorable prognostic factor in patients with pancreatic cancer.