The Role of Genetic Testing
By: David Sharp
Finding out whether you’ve inherited a cancer-causing genetic mutation from a parent can add an important puzzle piece to your prostate cancer diagnosis. That information can affect whether you should be screened for other cancers, whether blood relatives should also consider getting tested, and even which prostate treatments you might want to pursue.
The genes most closely associated with harboring inherited mutations that cause prostate cancer include BRCA1, BRCA2, HOXB13, ATM, CHEK2, PALB2, TP53, PTEN, MSH2, and MSH6. As they pass from one generation of a family to the next, these harmful mutations (also called pathogenic variants) put recipients at increased risk of developing other types of cancers, such as breast, ovarian, endometrial, colorectal, pancreatic, and melanoma.
A germline (inherited) genetic test can reveal whether you carry any of these variants. The test will check your saliva, a cheek swab, or your blood for inherited mutations. If you have one, it exists in every cell of your body. Testing positive doesn’t mean you’ll necessarily develop another cancer, but it indicates that extra monitoring will be warranted. Aside from any cancer-causing variants you might have acquired from a parent, cancer cells can make their own mutations. A separate analysis of your biopsied tumor tissue—called a somatic test—can show if that’s happened in your case.
Learning that you have a germline variant is a red flag that other blood relatives who may have inherited the same mutation should consider getting tested, too. A positive result could also influence your treatment choices. If you carry a BRCA2 mutation, for instance, your treatment options may expand to include PARP inhibitors, drugs that tend to work best in prostate cancers with changes in that particular gene.
Having prostate cancer raises the chance that you carry an inherited variant. One analysis found germline BRCA1/2 variants in 4.47% of prostate cancer patients overall and 5.84% of those with metastatic disease, compared with roughly 0.25% to 1% in the general population.
Family history matters, too. If blood relatives have had prostate, breast, or other cancers linked to inherited variants, the case for testing is stronger. The same is true if your ancestry is associated with higher-than-normal rates of certain variants. For instance, the incidence of BRCA-related variants is significantly increased among Greenlandic Inuit, Ashkenazi Jews, and people with ancestry from Whalsay, Shetland, or Orkney in Scotland. Breast cancer studies also suggest elevated inherited BRCA1/2 rates among patients from the Bahamas, Nigeria, and Trinidad and Tobago.
If you test positive, AnCan is ready to help. We host a quarterly online support group for people with inherited pathogenic variants. It meets on the second Thursday of each quarter at 8 p.m. Eastern in the AnCan Schmier Room. AnCan also offers an email list that makes it easy for men with prostate cancer and inherited mutations to share information.