Genetic Test For Breast Cancer Risk Amid Concerns Among Researchers

Main Category: Breast Cancer
Also Included In: Genetics
Article Date: 09 Oct 2008 - 5:00 PDT

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An Icelandic biotechnology company on Wednesday will begin offering a new genetic test to assess a woman's risk for the most common forms of breast cancer, reigniting concern about the proliferation of unregulated genetic tests, the Washington Post reports. FDA does not regulate screening tests when they are conducted by the labs that offer them. According to the Post, laboratories currently are offering genetic testing for more than 1,200 conditions. The $1,625 breast cancer risk assessment -- created by deCODE Genetics, of Reykjavik, Iceland -- uses a blood sample or cheek swab to examine seven genetic variations found in studies by the company and others to be associated with an increased risk for breast cancer. Patients receive results allowing them to assess their risk for common forms of breast cancer. Studies indicate the test result can tell women if they have less than half to as much as four times the average lifetime risk for breast cancer.

According to the Post, doctors currently use a variety of factors such as age and family history to assess a patient's risk for developing breast cancer. Women with a strong family history can get tested for two genes that increase their predisposition to breast cancer, but this test only account for 1% to 3% percent of breast cancers. The genetic variations detected by the new test account for about half the breast cancer cases in industrialized countries, including the U.S., the Post reports.

Eric Winer, spokesperson for the American Society of Clinical Oncology and a breast cancer expert at Harvard Medical School, said women who are told they have a lower than average risk "may feel they don't have to worry about breast cancer and can forgo standard screening test," while those who are told of a higher than average risk may react with "potentially unnecessary alarm." Mary-Claire King, a geneticist and breast cancer expert at the University of Washington, and others have questioned whether the genetic markers used in the deCODE test have been definitively linked to an increased risk of breast cancer. King said, "The idea of introducing into medical practi(ce) a test whose predictive value is completely unvetted biologically is frightening." Winer agrees that the test should be subject to much more testing, including studies validating its predictive value and whether women with increased risk would benefit from additional screening or medication. However, Kay Wissmann of the Chicago-based advocacy group Breast Cancer Network of Strength said the test "could provide information that could potentially help women make better decisions. It could empower them."

In addition, research on the test has mainly involved women of European descent, and "it remains unclear how accurate it would be for women of other backgrounds," the Post reports. FDA spokesperson Karen Riley said the agency had just been made aware of the new test and "can't speculate" on the test or whether the agency would take any regulatory action.

DeCODE CEO Kari Stefansson said the company is studying the accuracy of the test for women of non-European backgrounds. "This has been better clinically validated than any test I know," Stefansson said, adding that deCODE Genetics has "extraordinarily good statisticians who have probably the best track record in human genetics today" (Stein, Washington Post, 10/8).

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