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Genetic Testing is No Panacea for Patients

July 7, 2008

By Lisa Rosetta, The Salt Lake Tribune

Jul. 7–Shirley Carson wanted to give her daughters everything in the world — but this.

The news of her daughters’ positive test results for the BRCA I gene, which causes breast and ovarian cancer, was devastating.

“My biggest hurt is, ‘Now I’ve done it to both of my children,’ ” said Carson, who was diagnosed with breast cancer in 1996.

With the help of a genetics counselor, Carson’s daughters Kassy Spainhower and Jen Charlesworth were able to understand their test results and take action: They get clinical breast exams twice a year and mammograms annually. Harnessing the predictive power of genetic testing, they say, may save their lives.

“Everybody is looking far into the future and being very careful,” Carson said.

With more than 1,100 genetic tests now available — some marketed directly to consumers — and the federal Genetic Information Nondiscrimination Act signed into law in May, a growing number of people may seek clues from their genetic blueprint.

Genetic advances in diseases such as cancer hold promise for improved prevention, diagnosis and treatment. But the Carson family’s experience isn’t universal. Experts say the public, and some health professionals, do not fully understand when genetic testing should be done — and when it is, how the results should be interpreted and used.

For many proposed genetic tests, “the quality of the information needed to make decisions about patient care really isn’t there in the sense of clinical trials that say, ‘Yes, you should do this,’ or ‘no, you shouldn’t do this,’ ” said Marc Williams, director of Intermountain Healthcare’s Clinical Genetics Institute.

And with some conditions, there is no way to halt or reverse the disease.

Unraveling your DNA: So when does it make sense to seek out genetic testing?

First, it’s important to understand the likelihood of inheriting a particular gene, said Randall Burt, senior director of prevention and outreach at the Huntsman Cancer Institute.

All cancer is genetic — meaning the disease arises when there is a “mistake” in a gene, which then gets passed on to other cells.

Only 3 to 5 percent of the time, however, is a cancerous mutation directly passed on to other family members — most cancers develop during a person’s own lifetime.

For other diseases, however — such as Huntington’s — the odds of inheriting a mutated gene are much higher: about 50-50.

Generally, Burt said, a genetic test is only helpful if the diagnostic test is reliable, the results have the potential to make a difference in someone’s medical care and a patient’s likelihood of having a particular condition is high enough to justify the effort and expense.

“If there is at least a 10 percent risk of having the condition, then it’s probably worth sorting out,” he said.

Someone with a family history of colon cancer, for instance, would be a good candidate since it’s more likely that person is carrier of a mutation and, through rigorous screening, “we can pretty much prevent the cancer from ever occurring,” he said.

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Power of prevention: That’s something Lyle Gestal, who works at Alta during the winters, is counting on.

Her father, 58-year-old Dean Gestal, has battled multiple rounds of melanoma lesions that required disfiguring surgeries to remove. After testing positive for the CDKN2A/p16 mutation — carriers have a 76 percent lifetime risk of getting melanoma — doctors at Huntsman encouraged him to talk to his four daughters about getting tested. Only Lyle came back with a positive result — which she had expected.

The knowledge that she’s at high risk for melanoma like her father has prompted the 24-year-old — who works at the lift lines checking tickets — to be more diligent about taking care of her skin.

“It made me more cautious about putting [sunscreen] lotion on and wearing protective clothing,” she said.

Interpreting the results: A genetic test is most effective after a family member has been diagnosed with a disease and tested positive for a known mutation, said Saundra Buys, co-director of the Huntsman Cancer Institute’s Family Cancer Assessment Clinic. That signals to clinicians exactly what they should be looking for in the person being tested.

“What a lot of people want to do is get tested when they don’t have cancer,” said Buys, who is also the medical director of the High Risk Breast Cancer Clinic. “That’s a situation where it’s very rarely appropriate to do the testing, because most of the time they’re not going to have a mutation.”

At first blush, patients may think a negative result is good. But, as Buys explained, it’s more complicated than that.

If a woman with a family history of breast cancer is tested for the BRCA genes and her test comes back negative, there are two possibilities: one is that a gene mutation runs in the family, but she didn’t inherit it.

In that case, her risk of getting cancer still isn’t zero — it just means it’s the same as the general population’s lifetime risk (about 13.2 percent, or 132 out of 1,000 women, according to the National Cancer Institute.)

The other possibility is she did inherit a gene mutation, but one which has not yet been identified. In that scenario, her risk for breast cancer still would be higher, which calls for more aggressive screening.

Following up: Burt, a gastroenterologist, said, “If people are just going out there and getting tests because they want to know if they’re at risk or not, it doesn’t mean anything.” The physicians worry that the potential for misunderstanding genetic tests is high. If a patient doesn’t understand these nuances, a genetic test could actually lead to a worse health outcome.

“What we’re afraid people are going to do is go get a negative test and not get the screening they need — when really they [still may be] at increased risk,” he said. “And they’re at least at [the general] population risk.”

It’s a problem that can arise, Buys said, when oncologists who order genetic tests fail to send those patients with negative results to see a genetic counselor for more education.

“This kind of conversation isn’t happening routinely with these families,” she said.

Getting educated: This is where genetics counselors like Huntsman’s Wendy Kohlmann can play an important role.

“Our goal is to help educate people about genetic testing, help them think through the decision-making process,” she said.

That doesn’t mean they don’t explore how a patient is feeling about a test and how they might react to the results. Most patients, however, deal well with the outcome.

One study recently published by Huntsman researchers showed that revealing genetic test results for melanoma helps patients protect themselves. Even patients who learned they didn’t have the mutation did a better job of getting screened.

Other studies have shown that people who are tested for Huntington’s disease have lower anxiety levels — even if their results are positive, said Bonnie Baty, a professor of pediatrics and director of the Graduate Program in Genetic Counseling at the University of Utah.

“People who didn’t get an answer did the worst,” she said, adding: “I think a lot of people are planners. They want to make some life decisions around things.”

For 24-year-old Spainhower, who inherited the BRCA I gene from her mother, that means planning to get a double mastectomy and hysterectomy — after she has children.

With an 87 percent chance of getting breast cancer and a 44 percent chance of getting ovarian cancer by the time she is 70, Spainhower said, “it’s a no-brainer.”

lrosetta@sltrib.com

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