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Genetic Testing After Prostate Cancer

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Being diagnosed with prostate cancer is terrifying, and you understandably want to get treated as soon as possible. But there’s an important step you should consider to be certain you’ll get the most appropriate treatment for your type of prostate cancer—genetic testing. Available tests aid patients diagnosed with prostate cancer throughout the spectrum of the disease process. Knowing your DNA “profile” will not only guide your treatment (or active monitoring), but will also tell you whether other members of your family could carry a cancer risk.

What’s involved: The latest innovation is called germline testing and is typically done when the cancer is an aggressive form. Rather than testing tumor cells, this is a blood test. It looks for mutations in DNA damage repair (DDR) genes. If you have these mutations, it is harder for your cells to repair DNA. Since cancer damages DNA, you may be at risk for a more advanced or aggressive type of cancer. Genetic testing may also find another type of germline defect called mismatch repair genes, which respond to a different kind of treatment.

Determining your DDR status is especially important if your cancer is advanced, metastatic (meaning it has spread) or considered high-risk based on the Gleason score. Cancer cells are examined under a microscope and are assigned a Gleason score (the old Gleason system used numbers between six and 10…the newer Gleason Grade Group assigns a number between one and five). A high score means your cancer is likely to be aggressive.

DDR testing is also valuable no matter what type of prostate cancer you have if you also have a personal history of prostate cancer before age 50 or if there’s a history of breast, colon, endometrial, ovarian and/or pancreatic cancer in your family.

HOW GENETIC TESTING PINPOINTS TREATMENT

Two types of cancer drugs, PARP inhibitors and platinum chemotherapy, have been shown to work best on people with DDR mutations because they target DNA in cancer cells. People with mismatch repair genes respond better to cancer treatment called immunotherapy.

Another advantage to testing is that results may make you eligible to participate in a clinical trial testing a new treatment for advanced prostate cancer. Many trials look for patients with specific genetic defects.

HOW TESTING HELPS YOUR FAMILY MEMBERS

Your having germline defects can prompt your children and siblings to get genetic testing themselves to understand their cancer risk. Although prostate cancer is a male disease, it shares germline defects with other cancers including breast, colon, ovarian and pancreatic cancers. That means that your relatives could be at higher risk for any of these cancers. For instance, while the BRCA1 and BRCA2 genes are usually associated with breast cancer, they also have a strong link to advanced prostate cancer.

If a family member tests positive for germline defects, he/she can start cancer screenings at an earlier age. As an example, blood testing for prostate specific antigen (PSA) may be started at age 40 instead of the usually recommended age of 50.

Genetic counseling for men with prostate cancer is a field that is rapidly evolving. Leading groups such as the Prostate Cancer Clinical Trials Consortium, which includes prostate cancer researchers at leading cancer institutions across the country, recommend that men diagnosed with prostate cancer see genetic counselors promptly and discuss genetic testing. But for now, that’s just a recommendation rather than the standard of care. So you might need to bring up the subject with your doctor and ask for a referral to a genetic counselor to discuss the benefits of testing for you.

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Source: Jim C. Hu, MD, MPH, urologic oncologist and Ronald Lynch Professor of Urologic Oncology at Weill Cornell Medical College in New York City. Study titled “Evolving Intersection Between Inherited Cancer Genetics and Therapeutic Clinical Trials in Prostate Cancer: A White Paper From the Germline Genetics Working Group of the Prostate Cancer Clinical Trials Consortium,” published in JCO Precision Oncology. Date: November 29, 2018 Publication: Bottom Line Health
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