As cancer treatments become increasingly sophisticated, so too has the testing for this disease. Genetic tests that can determine one’s risk for cancer—or help guide treatment in those who’ve already been diagnosed—are now becoming the standard of care.

Latest development: For certain patients, Medicare will now cover cancer genetic tests that have been approved by the FDA—tests that detect whether your DNA has a genetic mutation that increases your risk of developing cancer or underlies a diagnosed cancer. Many private health insurers also are picking up the tab.

Whether you’re a woman or a man, the testing might show, for example, that you have a mutation (or variant) in the BRCA1 or BRCA2 gene, which increases risk for breast cancer by up to 85% or ovarian cancer by up to 60%…and risk for prostate cancer by up to 30% to 40%. 

For insights about the new world of cancer genetic testing, Bottom Line Health spoke with genetic counselor Scott M. Weissman, MS, CGC, a leading authority on this topic.

What’s Available

There are two main types of cancer genetic tests…

• Germline. A saliva or blood test is used to detect specific, heredity-based genetic mutations that may predispose you to cancer. If you already have cancer or you’re a cancer survivor, the test can detect whether it was tied to a hereditary cause—this will tell you if you’re at increased risk for a second ­occurrence of the same cancer or perhaps another type of cancer…or whether family members should also consider testing. Medicare typically covers this test only if you currently have cancer or are a cancer survivor. Most private insurers also cover people who have not had cancer. 

Germline tests can be obtained in three different ways…

Health-care provider–ordered.Following a risk assessment conducted by a doctor or genetic counselor who documents your personal and family history risk factors, a doctor may order the test. This type of test is 90% to 95% accurate.

Direct-to-consumer.In this case, you order the test yourself. You receive a kit, provide a saliva sample and send it back to the company. The DNA in the saliva is analyzed, and results are delivered directly to you. For example, 23andMe is the only company offering FDA-cleared direct-to-consumer cancer genetic testing—for BRCA1 and BRCA2 mutations in breast and ovarian cancer…and for MUTYH mutations, which raise the risk for ­colon cancer. Direct-to-consumer testing is not covered by insurance. 

Caution: The 23andMe BRCA test is only for the three genetic variants of the BRCA gene that are prevalent among Ashkenazi Jews—and misses the roughly 90% of people who have other types of BRCA mutations. 

Consumer-initiated, doctor-ordered.With this approach, you order the test from one of several laboratories (see below)—but the lab that conducts the test works with an independent network of genetic counselors and physicians to review the request, with a physician approving the test…or deciding that the test isn’t warranted. 

This type of testing (typically saliva) can detect dozens of genetic mutations that indicate an increased risk of developing certain cancers (such as breast, ovarian, uterine, colon, pancreatic, prostate, thyroid and brain). Many laboratories across the US now provide this service, but the three most reliable are Color Genomics…Invitae…and Helix/PerkinElmer. 

Helpful: The best laboratories are accredited by the College of American Pathologists, CAP.org, as well as Clinical Laboratory Improvement Amendments, CDC.gov/CLIA. To see if a lab that you are considering using is accredited, check the above websites or the lab websites…or call the lab and ask.

Watch out: Some unscrupulous laboratories are “cold calling” seniors and offering cancer genetic testing—whether the individual needs it or not. Before ordering, talk to your doctor about the benefits of the test. 

• Somatic. This test uses cancer tissue or blood to see if there is a genetic mutation fueling the cancer. This type of mutation spontaneously develops over the course of a lifetime and ­cannot be passed on to your children. If a mutation is found, the oncologist can prescribe one of the many “targeted” therapies now available to inhibit the action of the mutated genes. 

Examples:The EGFR mutation in lung cancer is targeted by the drug erlotinib (Tarceva)…and the BRAF mutation in melanoma is targeted by the drug vemurafenib (Zelboraf). Insurance almost always covers a somatic cancer genetic test, which must be ordered by a doctor.

Should You Get Tested?

If you’re interested in preventing cancer, it’s important to realize that only 5% to 10% of all cancers have a genetic component. When does genetic testing make sense if you have not had cancer? Some criteria… 

• When a close relative(a parent, sibling or child) has been diagnosed with cancer before the age of 50…or a cancer genetic test in a close relative shows a germline cancer mutation…or you have three or more close relatives with the same cancer regardless of age.

• For a woman, when there are both breast and ovarian cancers in close relatives…when there is breast cancer in two or more relatives on the same side of the family…when there is a close relative with cancer in both breasts.

For colon cancer,if a colonoscopy detects more than 10 precancerous colorectal polyps regardless of family history.

If you have cancer, you should get a cancer genetic test. Why this is impor­tant: Finding a genetic mutation can determine the best treatment options. 

Or if you had cancer years ago, before germline testing was common, and the cancer recurs, that could be a good time to do a risk assessment to see if a germline test is indicated.

Post-testing Strategy

If your screening test results are positive—meaning that you have a genetic risk for cancer—take action.

Your test results may indicate that you need earlier or more frequent screenings, such as colonoscopies. If you have a genetic risk for breast cancer, for example, along with earlier screening, you might also consider taking an estrogen-blocking drug or getting a preventive mastectomy.

And if you find out that you have a hereditary risk, you should also tell your close relatives (parents, siblings and children), as well as aunts/uncles, cousins and grandparents, that they should consider testing, too.  

Important: Even if your tests results are negative, if you have a strong family history of cancer, you may need increased monitoring. Ask your doctor for advice.

How Genetic Counseling Helps

It’s a complex process to decide whether or not to take a genetic cancer test…choose which test to take and which laboratory to use…understand the results…act on the results…and cope emotionally with positive results. That’s why there are genetic counselors—health professionals specially trained in genetics and psychology to help people in the process of genetic testing.

To find a genetic counselor near you: Go to the website of the National Society of Genetic Counselors, ­FindAGeneticCounselor.com, and enter your zip code. Some insurers will cover the cost of genetic counseling.