Breast cancer is the most common form of cancer found in American women outside of skin cancer. It is second only to lung cancer in cancer deaths. Over 200,000 American women will be diagnosed with invasive breast cancer during 2002 and almost 40,000 will die from it. The average woman in the US has a 10-12% chance of getting breast cancer in her life. However, for some women this risk is much higher. These women generally have a genetic mutation that is passed down from their mothers or fathers.

Everyone is born with two complementary copies of about 100,000 different genes- one copy from each parent. Cancer is a result of mutations (or mistakes) in these genes. A single mutation usually does not result in breast cancer. Genes in our cells mutate all the time. Normally the mutated gene is inconsequential. However, occasionally a genetic mistake occurs in a critical part of the cell’s makeup. As a single occurrence, this does not cause cancer. In fact, these first mutations may result in what we consider pre-cancerous cells. It takes several of these critical mutations to occur for a cell to become cancerous. In addition, certain lifestyle choices, such as smoking, increase the risk of these genetic mistakes. However, some women are born with one or more genetic mutations and it may take only one more mistake to convert that cell to cancer. These women are at a much higher risk of getting breast and ovarian cancer.

Hereditary Risks

Only 10 to 15% of all breast cancers appear to have a hereditary link. Most women get breast cancer as a result of random genetic mistakes. In the 1980s, researchers discovered the first genes proven to increase a woman’s risk for breast cancer. These genes, labeled BRCA1 and BRCA2 (BReast CAncer Gene1 and BReast CAncer Gene2), can be passed down from either the mother or the father. Between 1 in 400 and 1 in 800 American women carry the mutated version of this gene.

BRCA1 is a gene on the 17th chromosome that should suppress tumor growth. A mutation of this gene increases a woman’s risk of getting breast cancer 60 to 90% during her lifetime. That is because it may take only one more genetic mistake, instead of many, for the cell to become cancerous. In addition, between 20 and 60% of these women will develop ovarian cancer. BRCA2 is a gene on the 13th chromosome. A defect in this gene also increases a woman’s chance for both breast and ovarian cancer. Normally, both these genes help prevent cancer by making proteins that keep cells from growing abnormally. The mutations interrupt this process.
BRCA1 and BRCA2 are both associated with the development of breast cancer at an early age. Almost a third of women under age 29 who get breast cancer have one of these mutated genes. However, only 2% of women who develop breast cancer between the ages of 70 and 79 have one. These genes are also associated with prostate and colon cancer.

Testing Decision

Who should have genetic testing? The answer to this is complex because a positive result has medical, legal, and social implications. However, women who have (1)a family history of breast cancer under age 50, (2) two close family relatives with breast or ovarian cancer, or (3) a male relative with breast cancer are at increased risk and should have genetic counseling to help them with their decision. A close family member is considered to be one’s parent, sibling, aunt or uncle, or a grandparent on either the mother or father’s side. A genetic counselor will help you construct a family tree to help assess your risk. It should be remembered that a family history of breast cancer only increases the chances that a woman has one of the BRCA genes. It does not guarantee a problem. In fact, not every woman who has one of the BRCA genes will get breast or ovarian cancer.

There are many things a woman should consider before being tested for the BRCA genes. Genetic testing can affect relationships with family members. A woman should think about who in her family might want to know her test results, and whom she might want to tell. A woman may need to discuss her decision with her siblings and children. Should the test return positive results, it has an impact on them too. Children would have a 50% chance of inheriting the gene from her if she was positive for one of the mutations. Not everyone wants to know their risk.

Legally, the situation has been improving. The Kennedy-Kassenbaum Health Insurance Portability and Accountability Act of 1996, protects individuals from discrimination on the basis of health status, medical condition, claims experience, receipt of health care, medical history, genetic information, evidence of insurability and disability. However, these rights haven’t been tested in the courts with respect to genetic testing. Therefore, privacy issues should still be considered including the possible impact on future employment or qualifying for life insurance. To avoid these problems, some women have genetic testing within a research study so that it does not become part of their medical record and it therefore remains confidential.

Finally, a woman must consider the medical implications if her test comes back positive. Currently, the frequently recommended action for women who have one of the BRCA genes is to have a prophylactic bilateral mastectomy as a preventive step. However, even though the mastectomy reduces the risk of breast cancer by 90%, it does nothing to reduce the high risk of ovarian cancer. Recent studies at the University of Chicago Medical Center suggest that removal of the ovaries and fallopian tubes alone might be sufficient. According to their new studies (May 2002), removing the ovaries reduces the woman’s risk of breast cancer by as much as 75% and almost completely eliminates the risk of ovarian tumors. However, removal of the ovaries is recommended only for women over 35 or who no longer want children.

If a woman has already been diagnosed with breast cancer, she may want genetic testing prior to determining her treatment. For most women with early stage breast cancer, a mastectomy has similar results as a lumpectomy in combination with radiation therapy. If a woman is carrying one of the mutated genes, she might not want to choose the breast-saving lumpectomy. In addition, if a mastectomy is chosen, reconstruction is easier if the skin has not been radiated.

The Test

The test itself is a simple blood test. The blood can be drawn at your doctor’s office and then sent to a special lab where the genetic testing occurs. It takes 4-6 weeks to get the results. The cost can be $2600-$2700 to test for both genes. However, recently insurance companies have started to cover some of the cost of these tests.

Because scientific advances are being made every day, some of the above information may become out of date. It is recommended that all women considering genetic testing consult with their doctor and/or a genetic counselor for the latest information.