Genetic Testing For Cancer Recommended Only For High-Risk Women

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Genetic Testing For Cancer Recommended Only For High-Risk Women
By OHSU, Sep 8, 2005 - 1:01:38 AM

Primary care physicians should not routinely refer all women for genetic counseling and DNA testing to detect the presence of specific BRCA1 and BRCA2 gene mutations that may be associated with breast or ovarian cancers, according to a new recommendation from the U.S. Preventive Services Task Force. However, if a woman has certain specific family history patterns that put her at risk for these gene mutations, her primary care physician should suggest counseling and possible DNA testing. This is the first time the task force has addressed the issue of genetic counseling and DNA-based genetic testing for any disease.

The task force based its conclusion on a report created for the Agency for Healthcare Research and Quality (AHRQ) by a team of researchers at the Oregon Evidence-Based Practice Center (EPC). The EPC is a collaboration among Oregon Health & Science University, the Portland Veterans Affairs Medical Center, and Kaiser Permanente's Center for Health Research. The EPC is lead by Mark Helfand, M.D., M.P.H., professor of medicine (general internal medicine and medical informatics and clinical epidemiology) in the OHSU School of Medicine.

"Public interest in genetic testing is growing, and the tests are becoming more widely available. Understanding which women may benefit from genetic counseling and mutation testing for breast and ovarian cancer susceptibility will help primary care physicians appropriately advise their female patients," said Heidi D. Nelson, M.D., M.P.H., leader of the EPC research team that created the report. Nelson is a professor of medicine (general internal medicine and medical informatics and clinical epidemiology) in the OHSU School of Medicine.

The EPC research team analyzed existing scientific literature to determine the benefits and harms associated with primary care physicians routinely referring women for genetic counseling and mutation testing for inherited breast and ovarian cancer susceptibility.

BRCA1 and BRCA2 are genes that help control normal cell growth. Women who inherit specific mutations in one or both of these genes have a greater risk of developing breast or ovarian cancer, especially if their family members have had one or both of these cancers.

Risk for the mutations is relatively small. About 2 percent of women have the specific family history patterns that can put them at increased risk for these BRCA mutations and only about 1 in 300 to 1 in 500 women actually have the mutations. Even among women who test positive, only a proportion will develop breast or ovarian cancer, depending on the type of mutation and the type of cancer.

"Clinical guidelines for referral to genetic counseling and testing have existed for some years, but their effectiveness in primary care settings is still unknown. Counseling may help women better understand their cancer risks as well as the prevention, screening, and genetic testing options available to them," said Emily L. Harris, Ph.D., M.P.H., a genetic epidemiologist who is a senior investigator at Kaiser Permanente's Center for Health Research. Members of the EPC research team include OHSU School of Medicine researchers Rongwei Fu, Ph.D., assistant professor of public health and preventive medicine, and emergency medicine; and Laurie Hoyt Huffman, M.S., senior research associate in medical informatics and clinical epidemiology.

Women who are at an increased risk of inheriting the BRCA1 or BRCA2 gene mutations include those of Ashkenazi (predominantly Eastern European) Jewish descent with a first- or second-degree relative with breast or ovarian cancer. First-degree relatives include mothers, sisters or daughters; second-degree relatives include grandmothers or aunts. Other factors that put women at increased risk are specific family history patterns involving breast and ovarian cancer and multiple first- or second-degree relatives with one or both of the diseases. Risk level for these women is determined through detailed family histories and standard risk assessment tools.

Women who do not have a family history of either breast or ovarian cancer and are unlikely to test positive for the mutations should not be referred for testing, the task force emphasized, noting that there are potential harms involved in genetic testing. Women who test positive for genetic mutations may be vulnerable to job or insurance discrimination. Federal and state laws provide a degree of protection against discrimination on the basis of genetic information, but concerns persist. In addition, cost of the test can range from several hundred to several thousand dollars, and insurance policies vary regarding coverage of genetic testing.

For those women whose specific family history puts them at increased risk for genetic mutations and possibly cancer, counseling and BRCA mutation testing may offer significant benefits. Women who test positive can begin earlier and more frequent screening. Clinical trials show that chemoprevention reduces breast cancer risk. Also, the task force found evidence that women can reduce their risk of developing breast or ovarian cancer through surgical removal of the breasts or ovaries. The task force continues to recommend that all women, starting at age 40, should be screened for breast cancer using mammography.

The task force grades the strength of its evidence from "A" (strongly recommends), "B" (recommends), "C" (no recommendation for or against), "D" (recommends against), or "I" (insufficient evidence to recommend for or against). The task force recommends against routine referral for genetic counseling or BRCA testing for women whose family history does not indicate such an elevated risk (a "D" recommendation). The task force also recommends that women whose family history indicates an increased likelihood of harmful BRCA1 and BRCA2 mutations be referred for genetic counseling and evaluation for BRCA testing (a "B" recommendation).

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