(LifeWire) - Although the process of genetic testing for cancer starts out with a simple blood draw, the topic of genetic testing is anything but simple.
The test comes with a whole minefield of possible emotional aftershocks, especially for those who receive a positive or ambiguous result. When considering genetic testing, it's important to weigh all the pros and cons with a trusted physician. Most doctors will also recommend that families visit a genetic counselor before seeking the actual testing.
Who Should Consider Genetic Testing?
Each year more than 178,000 American women are diagnosed with invasive breast cancer. But of those, only 1 in 10 cases is what physicians would call "hereditary breast cancer."
Hereditary breast cancer may be associated with a number of inherited conditions; however, mutations on two genes, called BRCA1 and BRCA2, have been the most studied by researchers in women with breast or ovarian cancer. In the typical situation, genetic testing for breast cancer evaluate mutations in these two genes.
Exactly how common mutations of these genes are in the general population is not known; however, in one study, researchers examined the genetic profile of 1,628 women with breast cancer and 678 women without breast cancer who were between the ages of 35 to 64. They found that 1.4% of African-American women, 2.9% of Caucasian women and 10.2% of Jewish women had a BRCA1 mutation. The same study also found that 1.1% of Jewish women, 2.1% of Caucasian women and 2.6% of African-American women had a BRCA2 gene mutation.
Experts recommend that women consider testing for BRCA1 and BRCA2 mutations if they have a "significant family history" of breast or ovarian cancer. According to the National Cancer Institute, a significant family history is defined either as having "two or more close family members who have had breast and/or ovarian cancer" or as having "breast cancer in . . . family members [that] has been found before the age of 50."
The National Cancer Institute defines "close" as a first-degree relative, such as a parent or sibling, or a second-degree relative, such as a grandparent or aunt. Also, genetic counseling is recommended for any women who is diagnosed with breast cancer before the age of 45.
Anyone considering the tests should talk to a physician or a genetic counselor about the pros and cons. For help in finding such a healthcare professional or for more information about genetic testing, call the National Cancer Institute's Cancer Information line at 1-800-4-CANCER. To learn more about personal breast cancer risk, you may find the National Cancer Institute's breast cancer risk assessment tool useful.
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Robert Guy, National Cancer Institute
Considering the Cons of Genetic Testing
No medical risks are associated with genetic testing for breast and ovarian cancer, but test results can have a great affect on your life.
- Emotional health -- Both positive and negative test results can affect emotional health. Some studies indicate that people who receive a positive result are more likely to feel anxious about cancer. Although no studies have looked at how frequently this occurs, the National Cancer Institute reports that some individuals who have negative results experience survivor's guilt.
- Medical decisions -- A positive or negative test may affect what screenings or preventive steps a woman will choose to take throughout her lifetime. Those with a positive test result can choose from preventive actions that range from surgery to increased surveillance.
- Discrimination -- The Genetic Information Nondiscrimination Act of 2008 protects individuals from discrimination initiated by an employer or health insurance company. But the law does not include protection against discrimination when obtaining life insurance, short-term disability insurance or long-term care insurance. Those who test positive for a BRCA1 or BRCA2 gene mutation may struggle to acquire these types of insurance.
It's also important for families who are deciding whether to test or not to know that the results do not indicate with any certainty whether an individual will or will not be diagnosed with breast or ovarian cancer. The average American woman has a 12% chance of developing breast cancer in her lifetime. A positive test result means a 14% to 87% risk of developing breast cancer.
In about 10% of tests, the results are ambiguous. This typically means that the test wasn't able to identify one of the known BRCA1 or BRCA2 mutations that are linked to an increased risk of breast or ovarian cancer, but a genetic variant was discovered. People with an ambiguous test result are encouraged to talk to their physician about how to interpret these results.
Considering the Pros of Testing: Emotional Health
Although some studies link testing to an increase in anxiety, several others have found an association between declining to test and depression. One study found that among people with a significant family history of breast and ovarian cancers, those who declined testing had a significant increase in depressive symptoms 1 month after declining testing (from 26% at the time testing was offered to 47% at 1 month after declining the test). Reported symptoms of depression remained the same among those who opted for testing. According to the National Cancer Institute, it's not uncommon for individuals who choose testing to feel more "in control" of their health. Genetic testing allows individuals to take a proactive approach to their medical care.
Considering the Pros of Testing: Physical Health
Remember, a negative test does not mean that the individual will not be diagnosed with breast cancer, nor does a positive test guarantee an eventual breast cancer diagnosis. But genetic testing can provide individuals the information they need to make important decisions about medical care.
Those with a positive test can opt for any of a variety of prevention options, including:
- Increased surveillance -- The earlier cancer is caught, the more treatable it is. For most women, an annual mammogram starting at age 40 is recommended, as are annual gynecological visits beginning during the teenage years. For those with a BRCA1 or BRCA2 mutation, experts recommend beginning annual mammography at least 10 years prior to the earliest age of diagnosis within the family. Memorial Sloan-Kettering Cancer Center in New York recommends a clinical breast exam every 6 months. Women should consult their physicians about other methods of surveillance, such as MRIs.
- Chemoprevention medications -- As the name suggests, chemoprevention drugs are medications that are designed to lower one's risk of developing cancer. Two of the commonly prescribed chemoprevention medications -- Nolvadex (tamoxifen) and Evista (raloxifene) -- are approved for use among women over 35. It is recommended that these drugs be used for no longer than 5 years. A National Cancer Institute study found that "Tamoxifen reduced the risk of invasive breast cancer by 49% in women at increased risk for developing the disease." But few studies have been conducted to determine how these medications impact those with specific BRCA1 and BRCA2 mutations. Be sure to talk to a physician about possible side effects associated with medications such as tamoxifen and raloxifene. Tamoxifen has been linked to a host of side effects, including nausea, hot flashes and in rare cases, an increased risk of endometrial cancer.
- Prophylactic surgery -- This step involves the removal of tissue that is at risk for cancer before the cancer develops. Those with a BRCA1 or BRCA2 mutation can choose preventive mastectomy, hysterectomy, removal of ovaries and fallopian tubes, or any combination of these procedures. Prophylactic surgery has been shown to reduce the risk of breast and ovarian cancers by 90%.
"Breast Cancer Screening Guidelines." Cancer Information. 21 Apr. 2006. Memorial Sloan-Kettering Cancer Center. 17 Apr. 2008.
"Genetic Testing for Breast and Ovarian Cancer Risk." National Cancer Institute. 20 Mar 2006. U.S National Institutes of Health. 8 Jun 2008.
"Genetic Testing for BRCA1 and BRCA2: It's Your Choice." Cancer.gov. 6 Feb. 2002. U.S. National Institutes of Health. 8 Jun 2008.
"Genetic Information Nondiscrimination Act of 2008." National Human Genome Research Institute. 21 May 2008. U.S. National Institutes of Health . 8 Jun 2008.
Kinsinger, Linda, Russell Harris, Steven H. Woolf, Harold C. Sox and Kathleen N. Lohr. "Chemoprevention of Breast Cancer." Agency for Health Care Research and Quality. 2002. U.S. Preventative Services Task Force. 8 Jun 2008.
Lerman, C., C. Hughes, S.J. Lemon, D. Main, C. Snyder, C. Durham, S. Narod and H.T. Lynch. "What You Don't Know Can Hurt You: Adverse Psychologic Effects in Members of BRCA1-linked and BRCA2-linked Families Who Decline Genetic Testing." Journal of Clinical Oncology. 16: 5 (1998) 1650-1654. (subscription)
Malone, K.E., J.R. Daling, D.R. Doody, L. Hsu, L. Bernstein, R.J. Coates, P.A. Marchbanks, M.S. Simon, J.A. McDonald, S.A. Norman, B.L. Strom, R.T. Burkman, G. Ursin, D. Deapen, L.K. Weiss, S. Folger, J.J. Madeoy, D.M. Friedrichsen, N.M. Suter, M.C. Humphrey, R. Spirtas and E.A. Ostrander. "Prevalence and Predictors of BRCA1 and BRCA2 Mutations in a Population-Based Study of Breast Cancer in White and Black American Women Ages 35 to 64 Years." Cancer Research 66:16.(2006) 8297-308.