"Breast Cancer Genes": Myths and Facts

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All women have two copies each 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 either one of these tumor suppressor genes becomes damaged, the other copy can act as a "brake" on uncontrolled cell growth. Scientists have identified several other genes that may play a role in breast cancer risk.

Several hundred variations of the very large BRCA genes have been identified so far. Some of these appear to be linked to an increased risk of breast and ovarian cancer in certain families. 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. Most of these cancers do not seem to 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:

  • Testing positive may have devastating psychological effects. This can involve 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, immigration and other arenas.
  • Tests with limited predictive value may lead to women having unnecessary surgery, such as "prophylactic" mastectomies and oophorectomies (removal of the breasts or ovaries).
  • 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 240A Elm St. Somerville MA 02144 USA

Tel: (617) 625-0277
E-mail: office@bwhbc.org

Council for Responsible Genetics Tel: (617) 868-0870