Abstract ES6-3: Breast cancer genetic testing: moving from cancer risk assessment to therapeutic biomarker

In the last two decades germline genetic testing for breast cancer (BC) susceptibility has evolved from a single-gene analysis to a multigene cancer panel risk assessment tool. In addition, identifying a mutation in the BRCA1/2 genes may nowadays represent an opportunity for cancer targeted therapy. Current challenges in our routine clinical practice and for public health policies are to reconcile the implications derived from the identification of a hereditary cancer susceptibility that may impact beyond the person who is performing the genetic test, with and increasing and faster access to the test. Assessment of cancer risk was the first reason to incorporate germline BC genetic testing. As a consequence, mutation carriers are recommended specific screening and/or risk reduction options. While prophylactic bilateral salpingoophorectomy has shown a decrease in mortality and ovarian cancer-specific mortality, its role as a risk reduction option for breast cancer remains controversial. Radiologic imaging with magnetic resonance and mammogram has demonstrated beneficial in early detection of breast cancer, but risk reducing mastectomy may also be an option. Recent prospective data has shown that cancer risks differ between BRCA1 and BRCA2 mutation carriers, and that this estimation may be influenced by a combination of single-nucleotide polymorphism that constitute the polygenic risk score (PRS). Whether a more precise accuracy in cancer risk estimation in the short term (ie 5-10 years) may help to tailor screening and/or risk reduction options is unknown. As more BC-associated genes have been identified and technology has evolved, single gene testing has evolved to multigene panel testing. Available data suggests that patients can cope with multigene cancer panels although more research is needed to fully understand the psychosocial implications of multigene cancer panels, especially for those who have variants of unknown significance or moderate penetrance variants. Research is also needed to explore and develop communication models that maximize patients’ understanding and empower them to make informed decisions. The impact on reproductive-decision making will also be explored. Finally, a mutation in the BRCA1/2 genes is a predictive biomarker for targeted therapies in breast, ovarian, pancreatic and prostate cancer. Therefore, knowing the genetic status of our BC patients may influence their therapeutic options. The challenges and opportunities derived from new clinical scenarios that accompany these advances will be addressed during the educational session. Citation Format: J Balmana. Breast cancer genetic testing: moving from cancer risk assessment to therapeutic biomarker [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr ES6-3.