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CDC Advises Docs to Inform Patients of Limitations of DTC Gene Scans


Originally published July 29.

By Turna Ray

The Centers for Disease Control and Prevention posted video commentary this week advising doctors to discuss with their patients the limitations of gene scans marketed directly to consumers.

According to Muin Khoury, director of CDC's Office of Public Health Genomics, gene scans sold online by consumer genomics firms are still not ready for clinical use by doctors. "The promise of genomics in the practice of medicine is great and exciting, but today the use of personal genomic tests is still not ready for prime time," Khoury said in a video address to doctors and the general public.

The video, available here, is part of the "CDC Expert Series" collaboration between CDC and WebMD's Medscape, an online community for physicians, nurses, pharmacists, and other healthcare professionals.

Jeanette St. Pierre, health communications officer for OPHG, told PGx Reporter via e-mail that OPHG decided to focus the video on personal genomic tests since they are "a hot topic."

She added that the healthcare providers who are the primary audience of Medscape "may benefit from learning about key factors that should be considered in the development and evaluation of genetic tests for clinical practice."

For patients interested in the services offered by DTC genomics firms, the CDC is advising doctors to tell their patients to eat right, exercise, and keep an accurate record of their family's medical history, which can be more informative about an individual's health than gene scans that don't focus on the environmental and behavioral factors that are major contributors to health.

"Family health history is a very informative and inexpensive 'genomic test' that can be used right now. It reflects genes, behaviors, lifestyles, and environmental factors that are shared among relatives," Khoury said in the video. "Family health history can help healthcare providers assess the presence of many genetic conditions and whether patients and their relatives may have an increased risk for specific diseases."

Two years ago, the Office of the Surgeon General launched "My Family Health Portrait," an internet-based tool that runs on any home computer and allows people to record their family's health information. Earlier this year, Surgeon General Regina Benjamin announced that the "My Family Health Portrait" effort was adding new features enabling customers to link this tool to their Microsoft HealthVault account. This would allow consumers to share their family's medical history with their doctors and incorporate this data into their medical care.

The CDC's message to consumers and doctors comes on the heels of a Government Accountability Office investigation into the gene risk assessments and marketing practices of 15 consumer genomics firms. The report, which was issued at a congressional hearing last week, concluded that the genetic test results provided by DTC genomics companies were "misleading and of little or no practical use to consumers" (PGx Reporter 07/28/10).

Amid congressional scrutiny, DTC firms are also facing a tough regulatory climate, since the US Food and Drug Administration has expressed its intent to regulate tests marketed by these services as medical devices requiring the agency's stamp of approval (PGx Reporter 07/28/10).

To assess how doctors feel about personal genetic tests marketed to consumers, in 2008 the OPHG surveyed 1,880 healthcare providers. The survey, published in Genetics in Medicine, revealed that 42 percent of providers were aware of personal genetic tests, and just as many had been questioned by one or more patients whether they should buy such tests. Around 15 percent of providers had patients bring their test results to the doctors' office for review and discussion.

"Most of these healthcare providers said the test results changed some aspect of the patient's care, such as screening tests offered, and medications or dosages prescribed," Khoury said in the video. "CDC is concerned about such premature use of personal genomic tests by consumers because these tests are not 'ready for primetime.'"

DTC firms maintain that the information their services provide are for education only, and should not be used to make medical decisions without consulting a doctor. Some DTC firms, in light of the regulatory backlash, have backed away from the DTC model, and are increasingly partnering with wellness groups and doctors. And since DTC firms launched, some physicians, particularly catering to high-income clientele (since the tests can be pricey and are not reimbursed by insurance), have become hip to the use of genetics in their practice.

For example, Navigenics has a Physician Portal that allows doctors to access patients' genetic tests results showing their likelihood of response to certain drugs. The company also has a partnership with MDVIP, a collective of physicians spread across 25 states and Washington, DC, who practice preventative and personalized healthcare. These doctors get discounted access to Navigenics' service, allowing them to incorporate genetics into patients' annual physical examinations (PGx Reporter 12/10/08).

Believing it's too soon to incorporate genetic test results on disease predisposition in the care of their patients, CDC advises doctors to consider the tests' analytical validity, clinical validity, and clinical utility before using them in their practices.

In his video address, Khoury points out — just as health regulators and DTC firms themselves have acknowledged — that while the analytical validity of most of these tests is high, they are lacking in terms of clinical validity and clinical utility.

"Despite the many exciting advances in genomic discoveries for common diseases, there is quite a bit we don't know about how to use this information to improve health and prevent disease," Khoury said.

"For most diseases, we are still at the early stages of identifying the full list of genes that are associated with a particular disease," he added, citing diabetes, cancer, and heart disease as examples of complex common diseases that are caused by multiple genes as well as environmental factors.

At the congressional hearing last week, representatives from three DTC firms — Pathway Genomics, Navigenics, and 23andMe — invited federal health regulators to set industry standards for ensuring the clinical validity of their tests. 23andMe has written a letter to the National Institutes of Health and the FDA to ask them formally for just such guidance.

Where health regulators and the consumer genomics industry disagree is on the clinical utility question. Many experts and physicians have questioned the usefulness of estimating the risk of serious illnesses, such as cancer, based on SNPs that might account for just a small fraction of disease heritability.. Furthermore, learning that someone harbors clinically valid genetic anomalies, such as the APOE4 gene variant conferring increased risk for Alzheimer's disease, may be useless at a young age since there are no proven prevention strategies.

"There is virtually no information available that looks at the health implications of communicating genomic information and the balance of benefits and harms for using these types of tests," Khoury said. "Furthermore, many of the common interventions, such as smoking cessation, weight loss, increased physical activity, and blood pressure control, are beneficial for preventing and controlling many diseases, regardless of a person's genetics background."

Indeed, the advice Navigenics offers to customers who learn they harbor the APOE4 variant is to exercise, control blood pressure and cholesterol, maintain social connections, and manage a healthy diet.

In addition to genetic test results, 23andMe provides its customers the opinion of certain medical experts on particular gene-disease associations, and many of the views published on the company's site clearly discourage the use of genetics to predict the likelihood that someone will develop a disease.

For example, in a Q&A published under the company's breast cancer sample report, breast surgeon Ellen Mahoney of Stanford University states that a person's genetic makeup "rarely" affects her risk of developing breast cancer, and while some doctors may use genetics to assess the likelihood of developing the disease, this practice "is dangerous and should be discouraged."

Risk "is a concept that applies to populations, not to individuals," Mahoney says in the interview. "If you have one room with 500 healthy women who have absolutely no family history of breast cancer in it, and another room with 500 healthy women each with at least two or three relatives with breast cancer, take all 1,000 names, and then invite them back in 10 years to count the number of cases of breast cancer that developed in the 10 years in each room, you will most likely count more cases in the room full of women with a family history."

Ultimately, she continues, even a patient's family history won't help a doctor decide whether to biopsy a tumor.

DTC genomics firms, however, argue that although the strategies they provide to prevent or delay illness may be no different than the most basic advice one gets from one's doctor to eat right and workout, genetic data can be a powerful motivator in convincing patients to quit smoking or stick to an exercise regimen.

A high-profile example of this was the experience of NIH Director Francis Collins, who, after finding out that he had a high genetic susceptibility for type 2 diabetes, began exercising and lost 20 pounds. Collins had no family history of diabetes. So far, however, there have been no large-scale studies published showing that genetic information can improve patient compliance or inspire behavioral changes.

That may soon change as Eric Topol, director of the Scripps Translational Science Institute, is slated to soon release preliminary results from a study showing that genomic information encourages them to take positive action. Scripps is conducting this 10,000-people study with Navigenics, Microsoft, and Affymetrix (PGx Reporter 10/15/08).

In June, the National Human Genome Research Institute released results from a behavioral study of nearly 2,000 people enrolled in the Henry Ford Health System in Detroit, who were offered genetic testing to gauge their predisposition for type 2 diabetes, coronary heart disease, high blood cholesterol, high blood pressure, osteoporosis, lung cancer, colorectal cancer, and malignant melanoma.

In the study, "people with more habits that put their health at risk tended to favor genetics to explain their health conditions," NHGRI reported. However, the results also showed that "family history may be an effective motivator of health behavior change."

And study participants who had a family history of disease "placed greater value on pursuing genetic information and information about changing health habits than those without such a history," NHGRI found.