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Breast Cancer and Genetic Testing Introduction

Intensive genetic counseling is required before undergoing genetic tests for breast cancer. During this educational counseling session, the health care provider can fully explain the benefits and risks of genetic testing and answer any questions you may have.

You will also be required to sign a consent form prior to participating in any genetic tests. The form is an agreement between you and your doctor, showing that you have discussed the test and how its results might affect your family.

Here are some questions to consider when thinking about genetic testing:

  • Am I prepared to cope with the result? Are my family members also prepared, including my children and my spouse?
  • What are my goals for testing?
  • How would I use my test results? What will I do differently if the results are positive, or if they are negative?
  • Whom will I share my results with?
  • Would a positive test result change relationships with my family?

What Happens During Genetic Testing?

Most importantly, you'll need to obtain a family pedigree to determine if there is a cancer development pattern within your family. A family pedigree is a chart that shows the genetic makeup of a person's ancestors, and is used to analyze inherited characteristics or diseases within a family.

After outlining the family pedigree, a blood test can be given to determine if you have a breast cancer gene. Keep in mind that the vast majority of breast cancer cases are not associated with a breast cancer gene. In addition, scientists do not know all of the genes that can cause breast cancer, so doctors can only test you for the known genes.

When someone with a cancer diagnosis and a family history of the disease has been tested and found to have an altered BRCA1 or BRCA2 gene, the family is said to have a "known mutation." If an association between the development of breast cancer and a breast cancer gene is made, then all family members willing to participate in genetic testing are asked to give a sample of blood. For many people, knowing their test results is important, because this information may help to guide future health care decisions for themselves and their families.

How Do I Interpret the Genetic Test Results?

A negative genetic test means that a breast cancer gene mutation was not identified. If genetic testing has previously identified a mutation in your family, then a negative test means you do not carry the specific mutation that was identified in your family. Therefore, you would have the same risk as the general population. If a BRCA1 or BRCA2 mutation has not been previously found in your family, a negative result should be interpreted cautiously.

In such cases, there is still a chance you are at an increased risk to develop breast cancer due to potential mutations in genes other than those we currently can test for.

A positive test result means that a mutation known to increase the risk of breast and ovarian cancer was identified. Knowing your cancer risk may help guide important health care decisions for you and your family.

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Genetic Testing and Breast Cancer

Who Should Undergo Genetic Testing for Breast Cancer?

A woman with a family history of breast cancer has a lot of concerns. Among other things, she is thinking of her job, children, and husband, as well as how her medical insurance and health team will be able to serve her needs in the future should a crisis arise.

What are the facts about families that have multiple members with breast cancer?
Overall, inherited breast cancer disorders account for a small minority of breast cancers. Genes are the "messages" in each cell of the body that determine the ultimate design of our bodies. Genes can be damaged by the environment. Additionally, people can be born with defects in the genes that remove the body's defenses against cancers. Only in about 10% of all breast cancer cases is there actually a genetic defect that can be tested. This means that 90% of breast cancers are due to other causes. In fact, most cases of breast cancer occur in women who do not have a family history of breast cancer. A complex interplay between environmental and genetic factors affect the development of breast cancer, and all the key factors have not yet been identified.

Should I Be Tested for Genetic Mutations?

You may want to discuss genetic testing with your doctor if any of the following scenarios apply to you:

  • You have two or more blood relatives -- mother, sister, aunt, cousin, or daughter -- with premenopausal breast cancer or ovarian cancer diagnosed at any age.
  • You have been diagnosed with breast cancer, especially if it was diagnosed before you reached menopause, you have a blood relative with breast or ovarian cancer, or if you cancer in both breasts.
  • You have been diagnosed with ovarian cancer and you have blood relatives who have had ovarian or breast cancer.
  • You are related to someone (male or female) who has a BRCA1 or BRCA2 mutation.
  • You are of Ashkenazi Jewish descent and you have blood relatives who have had breast or ovarian cancer, or you have had breast or ovarian cancer.

What Are my Options if I Have a "Cancer Gene?"

Women in high-risk categories (first-degree relative with breast cancer, personal history of breast cancer, prior abnormal breast biopsy results with atypical ductal hyperplasia or lobular carcinoma in situ) and carriers of the genes associated with breast cancer may want to consider starting regular breast cancer screening at age 25 or 10 years earlier than the age of the youngest person with breast cancer at the time of their diagnosis.

Some women choose preventive (prophylactic) mastectomy to decrease the chances of developing breast cancer, although this doesn't offer complete protection.

Another approach includes using the anti-estrogen drug tamoxifen or raloxifene (also known as Evista), a drug used to treat osteoporosis, to help prevent development of breast cancer.

What Are the Potential Problems With Genetic Testing?

Genetic testing is not 100% accurate. If a test is negative, a person still has a chance of developing breast cancer. If the test is positive, there is still a 15% to 20% chance of not developing breast cancer.

Genetic testing is costly, ranging from about $200 to more than $2,000, depending on the type of test. Insurance policies vary in providing coverage for genetic testing.

The results of genetic tests won't be available for several weeks. The length of time it takes to get results depends on the tests performed and under what circumstances they are done.

Genetic testing is highly controversial in society today, and legislation has been enacted to protect individuals who may have a genetic risk of developing cancer from employment and insurance problems. The best course of action a person can take is to become involved with an established genetic registry that can counsel individuals with a genetic risk for cancer.

What Are the Benefits of Genetic Testing?

For some women, the benefits of genetic testing include the ability to make informed medical and lifestyle decisions while reducing the anxiety of not knowing their genetic background. Another benefit is the ability to make a proactive decision regarding prophylactic surgery. In addition, many women are able to participate in medical research that may in the long run decrease their risk of death from breast cancer.

What About My Privacy?

The Health Insurance Portability and Accountability Act (HIPAA) of 1996 prevents insurance companies from denying health insurance based on genetic information, and prevents them from using genetic information to demonstrate that a health condition existed before application was made for insurance. In addition, many states have passed laws or have legislation pending to address insurance concerns.

WebMD Medical Reference

SOURCES:

National Breast Cancer Coalition

Reviewed by Arnold Wax, MD on June 20, 2009

Last Editorial Review: 6/20/2009

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Reviewed on 6/20/2009
References
SOURCES:

National Breast Cancer Coalition

Reviewed by Arnold Wax, MD on June 20, 2009

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