Genetic testing for hereditary predisposition to breast cancer in the real world: Initial experience.

Abstract

Around 5%-10% of breast cancers are due to hereditary breast and ovarian cancer syndrome. Genetic testing is important to identify these cases, enabling the adoption of specific risk-reducing treatment strategies. To analyze the performance of genetic testing and its implications in patients with indication of genetic testing to identify hereditary predisposition to breast cancer. This is a retrospective observational cross-sectional study, including 176 patients with clinical indication of genetic testing for pathogenic variants related to breast, ovarian and pancreatic cancers (among others), managed from 1999 to 2021 in an Oncology private clinic located in the city of Teresina (PI), Brazil. There was a predominance of female patients (98.9%) and those with a family (91.0%) and personal history (64.2%) of cancer. In the study, 102 patients (57.9%) received genetic testing. BRCA1 and BRCA2 pathogenic variants occurred in 26 cases (90%). Another three PALB2 and TP53 pathogenic variants were detected. Eleven pathogenic variant carriers (38%) underwent risk-reducing surgeries. BRCA1/BRCA2 pathogenic variants occurred in around 25% of tested patients. Approximately 42.0% of the patients did not undergo genetic testing, despite clinical indication.