Family Matters: Know your risk for hereditary cancer
Written by Dr. Teng
When you see your doctor for your annual checkup or for another reason, you undoubtedly will get asked about your family history. Not only are we interested in family history of diabetes or heart disease, but we also will ask about history of cancer. This includes first, second, and third degree relatives, and their ages at the time of cancer diagnosis. Though you may be wondering, “why does this matter?” or “how is this related to my visit?” this information can help us know if your risk for certain cancers is higher than average.
A woman’s risk of developing breast or ovarian cancer in the general population by the age of 70 is 8% and <1%, respectively. However, for women who have an increased hereditary risk of developing these cancers, it can be as high as 87% for breast cancer and 44% for ovarian cancer. These are staggering numbers, and fortunately most women do not fall into this category. As specialists in women’s health, it is our responsibility to evaluate a patient’s cancer susceptibility based on personal and family risk factors.
Family members may share a genetic risk for developing cancer. This hereditary risk is defined as the presence of a single cancer or syndrome of malignancies in a family. Hereditary cancer occurs when a gene that normally helps to prevent cancer is altered, or mutated. For example, mutations in the BRCA gene are responsible for hereditary breast and ovarian cancer. These genes can be passed down generations, and we can see multiple family members (including male relatives) develop cancer. They may also develop cancer at an earlier age than average. There are also mutations that are sporadic, meaning they are random and are not passed down from your parents.
Recognizing these familial patterns allows us to create management strategies proven to reduce cancer risk. As gynecologists, we are particularly interested in family history of breast and ovarian cancer. However, any cancer history, including colon, pancreatic, stomach, skin, or even prostate cancer in male relatives, is important. If you are identified as having an increased hereditary risk, your doctor may refer you for genetic counseling and increased screening. Certain testing may be recommended at an earlier age with increased frequency and depth.
So who gets genetic testing?
Approximately 10% of breast and ovarian cancers occur in women with an inherited susceptibility. Patients with a personal or strong family history of breast and/or ovarian cancer, or known BRCA mutation in the family, will be recommended for testing. Similarly, those with prominent family history of colorectal or endometrial (uterine) cancer may qualify for testing for hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome). DNA from a saliva or blood test can be analyzed for these mutations.
What if my genetic testing comes back positive?
Having a positive result does not guarantee that you will develop cancer, however we know that it significantly increases the risk of developing it. Patients with a known genetic mutation will receive increased screening to improve cancer detection. For example, patients positive for the BRCA mutation will be offered increased surveillance with clinical breast exams and imaging. Your doctor will also discuss the option of prophylactic surgery to significantly reduce the risk of developing cancer. Thorough discussions with the genetic counselor will also identify those members of your family who need testing.
So what can I do to reduce my risk?
A lot of recent media attention to hereditary cancers was created when famous celebrities, such as Angelina Jolie and Christina Applegate, shared with the public that they had tested positive for BRCA mutations. Both of their mothers died of cancer at an early age, and both women decided to have prophylactic risk-reducing surgery with mastectomy. Ask your family members about any known history of cancer. Update your doctor on any changes to your family history, and communicate any concerns you may have. Women who know they have a family history of cancer should talk to their doctors and determine if they can take action to reduce their risk.
Helpful links:
http://ghr.nlm.nih.gov/handbook/inheritance/runsinfamily