October is breast cancer awareness month but many of us do what we can to raise awareness all year long, and this year is no exception. There has been much encouraging breast cancer news this year, including the identification of more breast cancer genes, improved screening and treatment technology, and a dramatic increase in the number of labs offering genetic tests. There has also been some confusing news, with some experts recommending that all women over age 30 consider genetic testing for BRCA1 and BRCA2 genes. It’s a lot for women to sort through.
Genetic Link to Breast Cancer
Let’s start with the basics. Approximately 5 percent to 10 percent of all women diagnosed with breast cancer inherited a gene or genes that raise their risk for the disease. Red flags signaling an inherited risk include:
- Being diagnosed early (before age 50 )
- Multiple people on the same side of the family with breast cancer or a related cancer such as ovarian, or colon cancer
- A male relative with a history of breast cancer or an aggressive form of prostate cancer
- A personal or family history of ovarian cancer
- A personal or family history of pancreatic cancer
Another 20 percent of women may have a cluster of breast cancer in the family, but the pattern may not be very strong. Since breast cancer is common, if the family is big enough, it is not uncommon to see more than one relative with breast cancer. Usually the breast cancers are diagnosed after menopause and there are healthy relatives connecting the women with breast cancers in the family. In addition, there are limitations to what genetic tests for breast cancer can and cannot tell a patient. Meeting with a genetic counselor to review your family history can help determine the odds that you have an inherited risk factor, estimate your personal chance of developing cancer, and discuss the available testing options.
Genes Linked to Breast Cancer
There are several different genes associated with an increased chance of developing breast cancer over a lifetime, and the level of risk varies with the specific gene. For example, Angelina Jolie reported that she had a BRCA1 gene mutation which increases a woman’s risk significantly, and she chose to have a double mastectomy to lower her risk. A gene called CHEK2 raises the risk moderately, as does PALB2, the newest gene linked to breast cancer, as well as pancreatic cancer.
Should All Women Get Tested?
Dr. Mary-Claire King, a well known hereditary breast cancer researcher, recently suggested that women in the United States who are 30 years of age and older be tested for the BRCA1 and BRCA2 genes regardless of their personal or family history and ethnicity. While it’s important to have this discussion, there are also several reasons to take pause.
Meeting with a genetic counselor to review your family history can help determine the odds that you have an inherited risk factor, estimate your personal chance of developing cancer, and discuss the available testing options.
First, the data used to make this recommendation was gathered in a very specific high-risk population: Ashkenazi Jewish men living in Israel. Currently testing is recommended for Ashkenazi Jewish individuals who have a personal or family history of breast or ovarian cancers. It is very difficult to take this data and apply it to the general U.S. population in a meaningful way. More importantly, there are many breast cancer genes that affect our health besides BRCA1 and BRCA2. Without an appropriate risk assessment by a genetic counselor to look at the pattern of cancer in the family and select the most appropriate genetic test, the test may provide false reassurance – or lead to an irreversible surgical decision.
Each individual has a different history and different life goals. Surgery to lower risk might be right for some women, but others might choose more aggressive monitoring, such as frequent mammograms, breast MRI, and breast exams. That’s why it’s important for doctors and genetic counselors to gather as much information as possible and help a patient sort through it to make the best choice for them.
Starting the Pre-Test Process
If you are concerned about your chance of developing breast cancer, and are contemplating gene testing, talk with relatives about the health problems that run in your family. If there are family members who have had cancer, find out what kind of cancer and how old they were at the time of diagnosis. If you choose to meet with a genetic counselor, this information would be very valuable.
Connect with a genetic counselor in your area using the Find a Genetic Counselor tool.
Joy Larsen Haidle, MS, LGC, is president-elect of the National Society of Genetic Counselors and a genetic counselor at the Humphrey Cancer Center in Minneapolis.