Genetic testing is now available to look for the presence of certain genes that are linked with cancers. Genetic mutations account for only a minority of overall cancer cases, although this may increase with further research. For example, only about 5-10% of breast cancer cases have been shown to be linked with a particular gene mutation. Also, it is important to clarify that not everyone with these gene mutations will develop cancer.
Mutations in either of the two human genes, BRCA1 and BRCA2, both of which occur in men and women, can lead to an increased risk of cancer. In women, mutations in these genes can lead to an increased risk of breast or ovarian cancer, some of which may arise before menopause. Lifetime risk in people with these mutations may be as high as 85% for breast cancer and 60% for ovarian cancer. Risk of colon cancer is also increased. In men, mutations in these genes can lead to an increased risk of breast or prostate cancer. In both men and women, mutations in the BRCA2 gene have been associated with increased risk of lymphoma, melanoma, pancreatic cancer, stomach cancer, gall bladder cancer, and bile duct cancer. People of Ashkenazi Jewish descent may carry particular mutations in the BRCA1 (2 different mutations) and BRCA2 (one mutation) genes and these can be detected with genetic testing.
While BRCA1 and BRCA2 mutations are the most commonly discussed gene mutations with regards to breast and ovarian cancer, there are other gene mutations associated with breast cancer and other cancers and conditions.
People without certain risks are not typically referred for genetic testing. When making the decision with your health care provider about whether you need genetic testing, many factors, including but not limited to risk level, have to be considered:
- You are more likely to have an abnormal gene if you have have two or more close family members with breast and or ovarian cancer and/or the breast cancer in the family has occurred before the age of 50.
- You may be more likely to have an abnormal gene if there are other cancers that run in your family.
- You may be more likely to have an abnormal gene if you are of Ashkenazi Jewish descent.
- If you already know that that a cancer gene exists in your family you would be more likely to have it.
- Testing positive may lead to options of preventive medications, surgery, or increased surveillance.
- Insurance may or may not cover some or all of the cost of the test.
- Testing positive may affect your ability to get certain insurance.
- Testing positive may allow you to alert other family members of their potential risk, but can also negatively your emotional state and your family relationships.
- "Detailed Guide: Breast Cancer. What are the Risks for Breast Cancer?" American Cancer Society. September 2010. http://www.cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_for_breast_cancer_5.asp.
- "Genetic Testing for Breast and Ovarian Cancer Risk: It's Your Choice." National Cancer Institute. U.S. National Institutes of Health. March 2006. http://www.nci.nih.gov/cancertopics/Genetic-Testing-for-Breast-and-Ovarian-Cancer-Risk.
- "Genetic Testing for BRCA1 and BRCA2: It's Your Choice." National Cancer Institute. U.S. National Institutes of Health. May 2009. http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA.
- "Cowden syndrome." Genetics Home Reference. A Service of the U.S. National Library of Medicine. March 2006. http://ghr.nlm.nih.gov/condition=cowdensyndrome.
- "Li-Fraumeni syndrome." Genetics Home Reference. A Service of the U.S. National Library of Medicine. January 2007. http://ghr.nlm.nih.gov/condition=lifraumenisyndrome.
- "PTEN." Genetics Home Reference. A Service of the U.S. National Library of Medicine. August 2007. http://ghr.nlm.nih.gov/gene=pten.
Last Modified: 4/7/2011