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"Breast Cancer Genes": Myths and Facts (download a .pdf version) All women have two copies of the so-called "breast cancer genes," BRCA-1 and BRCA-2. When functioning properly, these genes are thought to help suppress the growth of cancerous cells. If one copy of these tumor suppressor genes becomes damaged, the other copy can act as a "brake" on uncontrolled cell growth. Scientists have identified at least four other genes that may play a role in breast cancer risk. Several hundred variations of the BRCA genes have been identified so far. Some of these appear to be linked to an increased risk of breast and ovarian cancer. A woman born with one damaged version of a BRCA gene has only one working set of "brakes" for uncontrolled cell growth. If her second BRCA gene becomes damaged by exposure to carcinogens, the woman can develop cancer. BRCA variants, in and of themselves, do not cause cancer. However, women who inherit certain variants appear to be more susceptible to environmental carcinogens. Inherited mutations appear to play a role in only about 5% of breast and ovarian cancer cases. The remaining 95% apparently do not involve inherited mutations. It is now possible to test women to see if they have inherited an altered BRCA gene. Such testing offers few clear advantages: • A positive test for a cancer-associated BRCA variant will not tell you if you are going to get breast or ovarian cancer. It simply means that you have one of many possible factors which may increase your likelihood of getting cancer, and therefore may have a higher than "average" risk of developing this condition. • A negative test for a BRCA variant does not mean that you will not get breast or ovarian cancer. It means that your risk is approximately the "average" lifetime risk for breast cancer. One out of every nine women in the United States will develop breast cancer during her lifetime. • There is no known effective prevention for breast or ovarian cancer. The surgical removal of healthy breast and ovarian tissue is believed by some to lower a woman’s risk of cancer, but it cannot eliminate it. Getting tested can have many adverse effects: • Testing positive can have devastating psychological effects. This can impact not only the individual who is tested but her entire family, all of whom may share her genetic risk status. • Positive test results can lead to discrimination. Healthy people who carry genes linked to risk of future disease are vulnerable to discrimination in insurance, employment and other arenas. • Tests with limited predictive value may lead to women having unnecessary surgery, such as prophylactic mastectomies and oophorectomies. • The overemphasis on genetic factors in cancer, when environmental carcinogens are known to make major contributions, takes attention away from environmental clean-up measures that could, in fact, reduce the incidence of cancer. Current research has identified links between cancer and a host of nongenetic factors, including organochlorides, estrogen and estrogen-like chemicals, pesticides, radiation, bovine growth hormone, diet and exercise. The "geneticization" of cancer creates a blame-the-victim mindset that obscures these social and environmental factors. Until we have effective prevention strategies, tests for variants of so-called "cancer genes" benefit mainly the commercial companies that market them, who stand to make huge profits by exploiting women’s justifiable fear of cancer. For more information, contact: Boston Women’s Health Book Collective, publishers of the highly influential women's health book, Our Bodies, Ourselves. Telephone: (617) 414-1230 Website: www.bwhbc.org |
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