Implementing mainstream germline genetic testing in breast cancer across Europe.

The implementation of mainstream germline genetic testing in breast cancer patients has both benefits and challenges. Multiple aspects need to be considered for the outline of gene panels and the amount of pre-test genetic counselling. Mainstream genetic testing is mainly performed to stratify patients for targeted treatment. In addition, identification of germline pathogenic variants in cancer risk genes may have surgical implications, consequences for surveillance of other organs at risk of cancer, as well as family implications among relatives at risk. To ensure that patients are well informed, the introduction of mainstream genetic testing performed by non-genetic health care specialists requires an adapted pre-test counselling visit. Here, we review the literature and propose a web-based educational session and pocket guide to support implementation of mainstream testing in oncology practice.