Genetic tests already exist to help determine the possibility that a patient might get a certain disease. Insurers cover some genetic tests but not all. How do they decide?

"Regence ... will cover any test that is demonstrated to improve the health of its members," says Dr. Joseph Gifford, senior medical director of Regence Blue Shield. For example, some women with advanced metastatic breast cancer have a gene called HER-2. Testing can identify who carries this gene and who doesn't. Physicians sometimes prescribe a drug called Herceptin, which costs $25,000 a year.

"If you have the HER-2 gene, as 25 percent of women do, Herceptin is very effective," Gifford explains. "If you do not have the HER-2 gene, you're wasting your money and [then must endure] the side effects." Most insurers cover the HER-2 test, because it differentiates between patients who will benefit from treatment and those who will not.

Regence will not cover a genetic test unless there is good scientific evidence that the test results would lead to different treatments to produce the best health outcome for the patient. Even with that stringent test, Gifford says the industry is seeing a 20 percent annual increase in genetic testing. "It's really too soon to tell how P4 Medicine is going to work in the world of insurance," Gifford says.

"Regence ... will cover any test that is demonstrated to improve the health of its members," says Dr. Joseph Gifford, senior medical director of Regence Blue Shield.