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

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.