Liquid Biopsy Revealed HBOC Pedigree and Led to Medical Management Among the Relatives.

A hereditary breast and ovarian cancer (HBOC) pedigree was detected via liquid biopsy, and cancer prevention was initiated for the patient's daughter, after receiving a definitive result from BRCA genetic testing. A 48-yearold woman with ovarian cancer was administered precision medicine, which used cell-free DNA from plasma. The results revealed a pathogenic variant of BRCA1 as a presumed germline pathogenic mutation. We confirmed the germline pathological variant BRCA1 c.81-1G> A and suggested treatment with a PARP inhibitor. One of her three children had the variant, was diagnosed as an unaffected pathogenic variant carrier, and was advised to initiate surveillance.