Doc Talk: The facts about breast cancer risk and genetic testing
09/30/2013 2:04 PM
08/08/2014 10:19 AM
Breast and ovarian cancer are topics of concern for many women, regardless of their family history. The National Cancer Institute reports that almost 200,000 cases of breast cancer and 25,000 case of ovarian cancer are diagnosed annually in the United States. While the majority of these cancers are not caused by inherited risk factors, about 10 percent are hereditary and linked to a genetic mutation. The month of October – National Breast Cancer Awareness Month – is a good time to evaluate your risks and ensure you taking necessary precautions to prevent or detect cancer early.
Q: Do most women who develop breast cancer have a family history?
A: No. The majority of breast cancers (65 percent) occur in women who have no family history of breast cancer and are not linked to heredity or genetics. These nonhereditary cancers are called sporadic breast cancers.
The risk of breast cancer increases as a woman ages. Most breast cancer is found after the age of 50. If you live to 90, your risk of developing breast cancer is one in eight or about 13 percent, even with no family history. Therefore, all women over age 40 should be screened for breast cancer with annual mammograms, even if they have no family history.
Q: Do women with a family history have a higher risk than one in eight?
A: Yes. The actual risk depends on the number of family members with breast or ovarian cancer and the ages at which they were diagnosed. Risk depends on age, family history and several other factors including the age of first menstrual cycle and pregnancy, previous breast biopsies, and race.
Breast cancers that develop in women with strong family histories are known as familial breast cancer and account for approximately 25 percent of all cases of breast cancer. In some instances, family members may have an even higher risk of breast cancer than expected due to an alteration or mutation in their genes, which is called hereditary breast cancer. The lifetime risk in a patient with these altered genes could be as high as 87 percent.
Q: What are genes and what is the BRCA (breast cancer) gene?
A: We’re all born with two copies of about 30,000 different genes. One copy of each gene comes from our mother and the other from our father. Two genes in particular, BRCA 1 and BRCA 2, normally work to prevent breast and ovarian cancer. But, in some cases we can inherit a BRCA 1 or BRCA 2 alteration or mutation from either parent. This alteration interferes with normal gene activity and makes the person with the altered gene more susceptible to developing breast or ovarian cancer.
Q: How many people have the altered or mutated breast cancer gene?
A: It is estimated that about 10 percent of women who are diagnosed with breast cancer will have one of these altered genes. Men can also have the altered gene, which increases their risk of developing breast cancer, prostate cancer and pancreatic cancer. Men can also pass the gene on to their sons or daughters. Their daughters then have a very high risk of developing breast cancer.
Q: How do I know if I am at risk for this gene?
A: Having a blood relative who has tested positive for the gene is the most important risk factor. Other risk factors include a history of, or a family member with, breast cancer before age 50; ovarian cancer at any age; pancreatic cancer at any age; male breast cancer; both breast and ovarian cancer; breast cancer in both breasts, multiple close family members (including grandparents, aunts and uncles) with breast, ovarian or pancreatic cancer; or being of Ashkenazi or Eastern European Jewish descent.
Q: What is my risk if I have the BRCA 1 or BRCA 2 gene?
A: Those with the gene have a 50 percent chance of developing breast cancer by age 50. By age 70, the risk jumps to as high as 87 percent. The risk of ovarian cancer is as high as 44 percent, compared to just 2 percent of the general, non-affected population. Those found to have the gene – both with and without cancer – are typically advised to take more aggressive steps to prevent or treat cancer.
Q: If I have risk factors, can I be tested to see if I have the gene alteration in BRCA 1 or BRCA 2?
A: Yes. Those at risk are wise to be tested for early prognosis. Only a blood or saliva sample is needed although the gene sequencing analysis, which looks for altered genes, is quite complex. Most health insurance plans pay for the test for those patients with appropriate risk factors.