Jennifer was 39 and perfectly healthy, but her grandmother had died young from breast cancer, so she decided to be tested for mutations in two genes known to increase risk for the disease.
When a genetic counselor offered additional tests for 20 other genes linked to various cancers, Jennifer said yes. The more information, the better, she thought.
The results, she said, were "surreal." She did not have mutations in the breast cancer genes, but did have one linked to a high risk of stomach cancer. In people with a family history of the disease, that mutation is considered so risky that patients who are not even sick are often advised to have their stomachs removed. But no one knows what the finding might mean in someone like Jennifer, whose family has not had the disease.
It was a troubling result that her doctors have no idea how to interpret.
Such cases of frightening or confusing results are becoming more common because of a big recent change in genetic testing for cancer risk. Competing companies have hugely expanded the array of tests they offer, in part because new technology has made it possible to sequence many genes for the same price as one or two. Within the next year, at least 100,000 people in the United States are expected to undergo these tests. The costs, about $1,500 to $4,000, are covered by some, but not all, insurers.
The new tests build on the success of earlier ones for inherited risks of breast, ovarian and colon cancer, which can give people options for prevention, like getting screened more often, taking a drug to lower breast cancer risk, or having their breasts or ovaries removed.
But some doctors worry that the newer tests for up to 30 genes may open a can of worms, because the ability to find mutations has outpaced the understanding of what they mean. In some cases, tests find cancer-associated mutations for which there are no preventive measures, and the patient is left with a bleak prognosis.
Some genes were included "because they could be tested, not necessarily because they should be," said Dr. Kenneth Offit, chief of clinical genetics at Memorial Sloan Kettering Cancer Center in New York. He said that the testing companies are "rushing headlong into this era," and that "individuals are getting results we're not fully educated to counsel them on."
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