Hereditary breast and ovarian cancer syndrome: A misnomer?

10594 Background: Germline pathogenic gene variants (PGV) in homologous recombination deficiency (HRD) genes are traditionally associated with breast, ovarian, pancreatic, prostate and melanoma skin cancer. Recent evidence suggests other cancers may also be associated with these genes. We analyzed the prevalence of somatic HRD mutations in common, traditionally non-hereditary breast and ovarian cancer (HBOC) associated incident cancers in the US. Methods: Data were collected from the American Association for Cancer Research’s (AACR) Project Genomics Evidence Neoplasia Information Exchange (GENIE) database version 13.0 via cBioPortal (http://genie.cbioportal.org). This is a publicly available, multi-institutional database of next-generation sequencing (NGS) genomic profiles of tumor samples. The database was queried for all cancers with at least 20,000 incident cases in 2022, as reported by the American Cancer Society, excluding well established HBOC associated cancers – breast, ovarian, prostate, pancreatic, melanoma. Frequencies of somatic PGVs were reported for nine HRD genes currently included in National Comprehensive Cancer Network (NCCN) management guidelines for HBOC: ATM , BARD1, BRCA1, BRCA2, BRIP1, CHEK2, PALB2, RAD51C and RAD51D. Results: A total of 78,285 tumor samples across 12 cancer types were included. At least 1 somatic HRD was found in 6.8% of all included tumors. At least 1 HRD PGV was most common in: Uterine Cancer (694/5,760, 12.1%), Non-Melanoma Skin Cancer (127/1,209, 10.5%), Bladder Cancer (462/4,605, 10.0%), Colorectal Cancer (1306/14,625, 8.9%) Non-Hodgkin’s Lymphoma (5/58, 8.6%), Esophagogastric Cancer (356/4,649, 7.7%), Hepatobiliary Cancer (219/3,325, 6.6%), Lung Cancer (1,480/23,621, 6.3%), Kidney Cancer (113/2,564, 4.4%), Brain Cancer (420/10,206, 4.1%), Thyroid Cancer (89/2,246, 4.0%) and Leukemia (80/5,417, 1.5%). The most common PGVs across all cancer types were BRCA1/2 and ATM (Table). Conclusions: A pan-cancer analysis using NGS data demonstrates a substantial rate of somatic HRD PGVs in common, traditionally non-HBOC associated cancers in the US. These data raise the possibility that germline pathogenic variants in HRD genes could be associated with several more cancers than currently known, underscoring the need for studies evaluating risks of the aforementioned cancers in germline PGV carriers. Additionally, these findings present opportunities for trials evaluating the efficacy of HRD-targeting therapies in these cancers. [Table: see text]