Prevalence Of Pancreaticobiliary Cancer In Irish Families With Brca1 And Brca2 Mutations.

210Background: Germline mutations in BRCA1 and BRCA2 genes are associated with pancreatic ductal adenocarcinoma (PDAC), and more recently associated with increased risk of biliary tract cancers (BTC). This study assessed the prevalence, age and gender distribution of PDAC/BTC in BRCA1/2 positive families; compared to those of the Irish population. Methods: A review of all families referred to a national genetics clinic from 09/11/1997-01/06/2018 was performed following institutional ethics board approval. Demographics including age, sex and BRCA mutation status was collected in each case of PDAC/BTC. The BOADICEA algorithm was used to estimate the probability that an untested relative of a known BRCA1/2 mutation carrier with PDAC was a carrier. Results: 3252 distinct family pedigrees were reviewed, of which 1193 contained a proband who underwent testing for BRCA1/2 based on Manchester score ≥ 15. Among 128 BRCA2 positive families, 27 (21%) contained a 1st/2nd or 3rd degree relative with PDAC, of 116 BRCA1...