A recent JAMA study, of 3607 men with a personal history of prostate cancer, found that 17.2% were found to carry a hereditary genetic mutation predisposing them to cancer. Importantly, 37% of these men did not qualify (at time of testing) for genetic testing per the recommended expert guidelines and thus would not have been tested. https://jamanetwork.com/article.aspx?doi=10.1001/jamaoncol.2018.6760
A similar study in breast cancer patients found that basing genetic testing on established guidelines will lead to missing nearly 50% of those who carry a high risk mutation, which is why the American Society of Breast Surgeons now recommends offering genetic testing for ALL breast cancer patients.
Knowledge of being a carrier of any of these potentially deleterious mutations can help direct treatments, cancer surveillance recommendations (personal and family), prophylactic therapies and lifestyle changes.
If you are interested in getting a hereditary cancer genetic test, contact your oncologist to discuss whether they think it is appropriate for you. I offer the Color genetic test to anyone who is interested. Learn more here.