Mainstream germline genetic testing in metastatic prostate cancer

A proportion of men with metastatic prostate cancer has a hereditary predisposition to cancer. In our study, which included nearly 800 men with metastatic prostate cancer in 15 Dutch hospitals, we found such a hereditary cancer predisposition in almost 6% of patients. Because it is hereditary, this alteration may also be present in the patients’ relatives. These family members have an increased risk of developing cancer. In individuals with such a hereditary predisposition, the risk of breast cancer is increased among female relatives, and the risk of ovarian cancer may also be elevated. Male relatives might have an increased risk of prostate or breast cancer. This thesis focuses on genetic testing in patients with metastatic prostate cancer. Traditionally, genetic testing is requested by a clinical geneticist. In this thesis, however, a new ‘mainstream genetic testing approach’ was used, in which genetic testing is discussed and requested by the patient’s treating healthcare professional instead of a clinical geneticist. Within our patient population, this could be a urologist, oncologist, nurse specialist, specialized nurse, or a physician assistant. In total, 69 healthcare professionals followed an online training module of 45 minutes to update their knowledge on genetics in prostate cancer and inform them on the workflow and filled out the questionnaires. This thesis demonstrates that these healthcare professionals have a positive attitude toward mainstream genetic testing and consider the required time investment to be feasible. Patients showed favorable outcomes with respect to anxiety, decisional conflict, and regret. In addition, patients who carry a hereditary predisposition felt confident in communicating this information to their family members. Finally, we identified several risk factors that increased the likelihood of detecting such a predisposition. Those risk factors are currently included in national genetic testing guidelines.