How genetic testing is used for cancer prevention & treatment

10:21 AM, Oct 08, 2019
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Cancer may not bring DNA and genetics to mind, but all cancer is caused by gene damage. Treatments in the past have typically meant surgery, radiation, or chemotherapy — sometimes all three. Now, oncologists have added DNA testing to their treatment tools.

There are two major uses for genetic testing in cancer care. One is testing DNA to determine cancer predisposition, which is also referred to as Hereditary Cancer, and the other is testing the tumor itself to look for DNA changes that can be targeted with personalized treatment.

Up to 10 percent of cancers are thought to be related to an inherited gene mutation, according to the American Cancer Society .

“We test patients for cancers that get passed down,” said James Maher, MD, PhD medical director of the TriHealth Cancer Institute . “It’s called cascade testing. If you look at the top of the waterfall, you may have one patient who had the cancer, and you start testing other family members to determine their risk of developing that same or other cancers. There was one family where I believe 10 people ended up being positive for a gene that can cause kidney cancer.” Cascade testing in family provides more than knowledge about risk, it allows those relatives to take advantage of early screening or cancer prevention options in many cases.

Another reason for genetic testing is to test a tumor, so doctors can tailor treatment, said Courtney Rice, MS, a Licensed Genetic Counselor for TriHealth .

“We use these tests to ask ourselves, ‘Is this tumor being driven by genetic weaknesses that the medical team can attack with a clinical trial or drug that might not have otherwise been used for this patient?’” Rice said.

Genetics combined with oncology, pathology, pharmacy and nursing create a multidisciplinary approach to precision medicine at TriHealth, changing the way cancer is treated.

“When I treat for melanoma, chemotherapy is no longer considered,” Dr. Maher said. “I test the tumor to see if can target the tumor with oral medications that specifically turn off that DNA gene change. We also use immunotherapy that is targeting the cancer through immune system stimulation. We test for the genetic makeup of the patient and tumor to see how we can care for the patient.”

Before precision medicine and genetic testing, there wasn’t much deviation from standard treatments, according to Dr. Maher.

“When someone came in with lung cancer, we used to give two combined chemotherapy agents,” Dr. Maher said. “Then we found there were specific mutations in lung cancer tumors that we could target and turn the tumor off. When patients have a certain mutation, we don’t even do chemotherapy. We give them an oral pill that targets that mutation.”

Testing also helps kickstart difficult conversations about cancer in families, said Rice, who has performed genetic testing for TriHealth for eight years.

“So many people have cancer in the family and the perception is, ‘We’re just waiting for it to happen,’” she said. “We want to change the dialogue around that. For many families, we can use genetic testing to understand their risk and then offer the most appropriate screening for early detection and discuss cancer prevention options while people are healthy. And, if a cancer is diagnosed, using a genetic test may give that one person options for treatments that are beyond the usual treatment options.”

TriHealth has a hereditary cancer program with six genetic counselors. They review family history, explain testing options, and go over possible implications for family members. They also send blood or saliva for testing, with results available in about three weeks.

It’s essential for people to involve a Licensed Genetic Counselor in their testing process not just a swab-and-mail kit at home, Rice said.

“There are few regulations in the genetic testing space, Direct to consumer genetic tests are marketed as comprehensive medical tests, but they aren’t,” Rice said. “Most direct to consumer tests are not an appropriate test for medical decision making. With DTC tests there are opportunities for falsely alarming and falsely reassuring a person — a genetic counselor can explain limitations of DTC and determine if additional genetic testing is necessary.”

If you have cancer in your family history and want to have discussion about cancer testing, contact the TriHealth Cancer Institute or call for an appointment with a genetic counselor at 513-853-1449.

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Cancer in your family? You may be at risk if any of the following are true:

· A close family member had a cancer diagnosis before age 50 (parents, siblings, children, grandparents, aunt, uncles, or first cousins).
· You have three relatives with the same type of cancer on the same side of the family.
· You have a male relative with breast cancer.
· You have a family member with pancreatic cancer.
· You have a family member with aggressive (metastatic) prostate cancer.
· You have more than 20 colon polyps.
· You have a relative who has a genetic mutation for cancer predisposition.

To make an appointment with a TriHealth genetic counselor, email tcigenetic@trihealth.com or call 513-853-1449.

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