Q What can you tell me about the breast cancer gene? If my grandmother had breast cancer should I be tested? — L.M., Walhalla
A There are two human genes that have been identified as BRCA1 and BRCA2. The genes are known to be tumor suppressors. In a normal cell, the BRCA1 and BRAC2 help to prevent uncontrolled cell growth by stabilizing the DNA. A mutation in either gene is associated with the development of hereditary breast and ovarian cancers.
The genes have been named breast cancer susceptibility gene 1 and breast cancer susceptibility gene 2. The first two letters in breast and cancer were used as an abbreviation for referencing the genes. The National Cancer Institute (NCI) estimates that inherited BRCA1 and BRAC 2 mutations account for 5 percent to 10 percent of breast cancers and 10 percent to 15 percent of ovarian cancers.
Other gene mutations are also associated with hereditary breast and ovarian cancers. For this reason, it is helpful that a family interested in genetic testing because of a family history of breast cancer talk with a genetic counselor. The genetic counselor can do an assessment of the family and determine the appropriateness of screening and also which screening tests should be used. A blood sample is used and the results usually take weeks to be completed. The testing can be expensive, so check with your insurance company as well. The cost will be several hundred dollars.
Certain populations are at higher risk for mutations in BRCA1 and BRCA2. Ashkenazi (Eastern European) Jewish populations have a higher frequency of carrying the mutated genes. Other ethnic or geographic populations include Dutch, Norwegian and Icelandic women. Overall white, non-Hispanic women in the United States have the highest rate of breast cancer; however, in women age 40 to 50, African Americans have a higher rate. Unfortunately, the death rate for African Americans is higher, which has been linked to the extent of the disease at diagnosis.
The NCI does provide a caution regarding the research on BRCA1 and BRCA2. The studies were done on large families with many incidences of cancer. The estimates of cancer with the gene mutation also can be related to other genetic or environmental factors. As more information becomes available, the statistics may change.
In trying to decide if genetic testing is important to your family, the guidelines are provided for women who are not of Ashkenazi Jewish descent and those with Ashkenazi Jewish descent. You may want to develop a family chart indicating who has had cancer and what age they were when they were diagnosed.
The genetic counselor would want to know if the person with cancer was a first degree relative (mother, daughter, sister) or second-degree (grandmother, aunt) or a combination of firs-t and second-degree relatives. The second question is the number of family members who have breast cancer and/or ovarian cancer or both. Breast cancer in a male relative would be important to note on your chart as well.
While no formal guidelines are recommended by NCI, patterns of familial cancer are used to suggest genetic testing. Once you have your family tree completed, look for two first degree relatives with breast cancer and one diagnosis under 50 years of age. Do you have a first-degree relative with bilateral (both breasts) breast cancer? Does your family have three or more first- and second-degree relatives with breast cancer? Is there a combination of first- and second-degree relatives with cancer of the breast or ovaries? Is there a combination of relatives with ovarian cancer? For Ashkenazi Jewish women, any first-degree relative with either cancer or two second-degree relatives on the same side of the family would indicate the need for genetic testing.
A positive test for the BRCA1 and BRCA2 just means that you carry the genetic mutation. You are at risk for developing breast cancer, but may not develop cancer. You will want to discuss the results with your doctor and plan for regular screenings (mammograms, MRIs, self-breast exams). Some physicians will recommend Tamoxifen or Evista (raloxifene) to reduce the risk of breast cancer. Screenings for ovarian cancer may include ultrasounds and blood tests for cancer antigens. Life style does influence the risk of developing cancer. Diet, exercise, smoking and alcohol use make a difference.