Are you at Risk?

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Gene Testing for Breast Cancer

About 80 percent of breast cancer patients have no family history of breast cancer. Another 15 to 20 percent of breast cancer patients have some family history of breast cancer which may indicate a genetic susceptibility. Between 5 and 10 percent of breast cancer patients have a very strong family history of breast cancer which is considered hereditary. Hereditary cancer can apply to the occurrence of breast cancer in closely related family members on one side of the family across generations such as one’s mother, aunt, daughter, grandmother, and great aunt. It can also apply to more than one occurrence of early onset (under age 50) breast cancer, the incidence of cancer in both breasts in an individual family member, or to the presence of male breast cancer in the family.

Mutations in two particular genes — named BRCA1 and BRCA2 — account for most hereditary breast cancers. The following statistics illustrate the power of these mutations. The general population has a 7 percent chance of getting breast cancer; people with the BRCA1 and BRCA2 mutations have a 55 to 87 percent chance. Both males and females have an increased risk of other types of cancer with either gene mutation.

Although genetic testing can be done simply by taking a sample of blood, it is important to carefully weigh the decision and discuss it with one’s oncologist and a genetic counselor on his or her professional team prior to testing. The DNA testing process is complicated and is performed only at specialized medical laboratories which results in high cost. All 50 states have laws protecting those who undergo genetic testing from having their results used as evidence of a pre-existing condition. Protection is also offered by the Health Insurance Portability and Accountability Act and the Americans with Disabilities Act of 1990. There are a few exceptions, however, which bear investigation before testing is done.

Genetic testing should be done with a family member who has already been diagnosed with breast cancer because she is most likely to have the mutated gene if one exists. Since the testing is quite expensive, she should first contact her health insurance company to see if some of the costs of testing are covered by her policy. If testing is done and either mutation is found in her DNA, any follow-up testing for family members is a simpler and less costly process.

Test results are considered very reliable. A genetic counselor is specially trained to understand and explain the statistical probabilities derived from testing and clarify the result obtained. It isn’t as simple as “you have it” or “you don’t have it.” There are four possibilities-- positive, ambiguous, or one of two types of negatives. Along with a personal consultation, the genetic counselor uses simple graphs, charts, and layman’s terms to make the process understandable.

If a mutation is found, the only conclusion that can justifiably be drawn is that family members are at increased risk. A positive result does not make breast cancer inevitable, but it does allow decisions to be made about more frequent screening, the addition of advanced screening methods, preventive surgery options, or preventive drug treatment. A negative result can bring reassurance to family members that their — and their daughter’s and granddaughter’s— chances of getting breast cancer are no greater than those of the general population. The knowledge of the results may open up Pandora’s Box. Therefore, adult daughters and granddaughters should only be given test results if they want to know. All genetic testing decisions are very personal, and should be the individual’s choice.

by GIGI