Game Changer?

Researchers are studying how much influence genetic test results have on health behavior.

By Aimee Swartz featured image
Illustration by Rebekka Dunlap

Tammy Schuler was elated when a cousin from her father’s side of the family found her through Schuler’s father and his siblings had lost contact with his mother and her family when he was a small child in the 1950s. They had been searching for relatives on that side of the family for years.

But Schuler’s joy was soon tempered when she learned that both breast and ovarian cancers ran in the paternal side of her family, and that many generations of women had died of the diseases. She began to wonder if the diseases were hereditary and, after talking it over with her doctor, she decided to have genetic testing to find out. “My father’s family history was a big red flag that testing should be done,” she says.

Genetic testing identifies changes, or variants, in genes. Some variants can increase the risk of developing serious health conditions, such as cancer. Genetic testing can also be used to select more effective drug treatments for certain diseases.

Schuler, whose family history suggests she may have inherited a cancer-causing mutation, was screened for a panel of variants, some of which could dramatically increase her risk of developing breast cancer, ovarian cancer, or both in her lifetime.

Scott Weissman, a genetic counselor at Chicago Genetic Consultants in Chicago, is quick to point out that “having a cancer-causing mutation does not necessarily mean a person [will] develop cancer.” But if people know they are at a greater risk of developing a disease, he adds, “the hope is they can make a choice to modify their behavior that may help improve their odds.”

But translating DNA-based risks into health benefits or even into action is not always a given. “Most people face some tough decisions,” says Weissman. “Some people change their lives. Some people change nothing.”

A recent meta-analysis (a study of studies) published in the British Medical Journal (BMJ) suggests the latter happens much more often. Researchers found genetic testing that indicated an increased risk of developing a disease had little to no impact on whether a person went on to adopt a healthier lifestyle, even if doing so could lessen disease risk. The researchers defined healthy behaviors as smoking cessation, exercising, eating right, or taking medication to prevent disease. It did not include behaviors such as prophylactic surgeries or regular screenings, both of which they referred to as “clinical means of reducing risk.”

For the analysis, researchers from the University of Cambridge culled 10,000 abstracts for studies that evaluated testing for genetic variants that affect a person’s risk of developing diseases for which there are known behavioral interventions, such as heart disease and cancer. The researchers then narrowed their investigation to 18 randomized and quasi-randomized studies that followed people after they received the results of genetic tests.

The BMJ study found that people who learned about their disease risks from genetic tests weren’t inspired to exercise, eat healthily, or stop smoking; nor were they inspired to wear sunscreen, drink less alcohol, or take medicines that could prevent diseases. In fact, researchers found that genetic testing had no significant behavioral effects whatsoever, prompting them to argue that genetic testing should not be used to improve people’s health via behavior change.

Hard Habit to Break

Jehannine Austin, an associate professor at the University of British Columbia, the president of the National Society of Genetic Counselors, and a member of Genome’s scientific advisory board, is not surprised. “It’s foolish to imagine that information alone is going to do something as fundamentally important as change behavior. If all we needed was information to change our behavior, nobody would be obese. Nobody would smoke.”

Austin believes that a behavior change requires not just the provision of genetic test results, but that those results be integrated into a patient’s “holistic understanding of the disease … being tested for, its causes, and ways to prevent it from worsening or developing” in the first place.

That’s where genetic counselors enter the picture. Genetic counselors have expert knowledge of genetics and genetic risk assessment and are not only qualified to help people understand their genetic testing results, but to help them use this information to make informed decisions about their health care.

“Genetic counselors can help people understand what information the test will provide, what it will not, and what to do with the results of the test — if anything. We can also help you decide if having a genetic test is the right choice for you to begin with,” Austin says.

Genetic counselors are also skilled in dealing with the many emotions genetic testing may provoke. Addressing these emotions, says Austin, “empowers patients, and empowerment, we know, is a precursor to behavior change.”

Changing Their Ways

Despite the limited impact of genetic testing on most people’s behavior, there are exceptions.

For example, women who learn they have BRCA1 or BRCA2 mutations are more likely to adhere to recommended mammogram screening intervals and more likely to take part in follow-up ovarian cancer screening. Others, such as actor Angelina Jolie, take additional risk-reducing measures. After testing positive for a mutation in the BRCA1 gene and in light of her strong family history of both breast and ovarian cancers, Jolie elected to have a preventive double mastectomy and to have her ovaries, uterus, and fallopian tubes surgically removed to lessen her chance of developing cancer. Some argue that these actions are indeed “health behaviors.”

Moreover, a handful of studies have shown that knowledge of genetic risk may indeed change health behaviors as defined by the BMJ’s meta-analysis. One study, for example, showed that people who learned through genetic testing that they were at risk of hereditary melanoma made behavioral modifications — regular skin self-exams, wearing sunscreen and protective clothing, and avoiding UV light exposure — to reduce their risk of developing the disease. That said, the study, which was not randomized, had limitations. Participants in the trial had volunteered to be in a long-term research project to study the utility of personal genome information in patient care. Therefore, those participants may have been more interested in their genetic risk for disease already and more motivated to change their behavior.

This concept of selective bias is something that has bothered Cinnamon Bloss, a clinical psychologist and an assistant professor at the University of California, San Diego’s department of psychiatry. She wonders whether people who are caught off-guard by genetic risk information are more or less likely to change their behavior. “When we talk about integrating genetic testing more broadly, the current body of literature is somewhat useful. But how do you study people who don’t want to sign up because they don’t want to know their genetic risk for disease? Would they be thrown by the information?”

The Way Forward

In the beginning, Schuler wasn’t sure which side of the fence she would end up on. “I didn’t know what I’d do if my tests came back positive for a BRCA mutation or something similar. Would I get prophylactic treatment, like a mastectomy?” Schuler says.

Though she ultimately tested negative for BRCA mutations, Schuler did test positive for a variant of unknown significance (VUS) on a gene called RAD51C. A VUS may or may not be associated with an increased risk of disease — in this case, both breast and ovarian cancer. The information, along with her family history and recommendations by both her physician and the genetic testing company that gave the test, prompted her to enroll in a program that tailors early surveillance breast cancer screening to higher-risk women. She is also eating a healthy diet, limiting alcohol, and exercising regularly in an attempt to lower her overall risk of developing breast or ovarian cancer.

If Schuler is just one of the reportedly few people who adjust their health behaviors in light of genetic test results, where does that leave the rest, who need more motivation for change?

“It’s a tough question,” says Bloss. “Health behaviors are so incredibly difficult to change. Billions of dollars are spent on weight loss.”

But she is not without hope.

“One thing I’ve always thought about is that even if people don’t want to take care of themselves, they want to take care of their families. I would like to see an intervention that might capitalize on the shared nature of genetic information among families,” she says.

She gives the hypothetical example of a mother who discovers through genetic testing that she has an increased risk for cardiovascular disease. While she still might eat a hamburger, she won’t serve one to her son who shares her genetic risk.

But she is much more optimistic about the effectiveness of genetic testing at prompting people to take clinical measures to reduce risk.

“I think that there is evidence out there that people will be more likely to engage in clinical means of reducing risk, like accelerated screening. Because it’s easier to go to the doctor every six months [for a screening than it is to eat healthy] every day.”