BRCA1 and BRCA2 Summary
Since BRCA1 and BRCA2, the so-called breast cancer mutation genes, were identified in 1994, a great deal more has been learned about them and their impact on gene carriers. It is important to remember that more than 80% of women who are diagnosed with breast or ovarian cancer do not carry one of these genes. Even some women in families where there has been a lot of cancer test negative for these mutations. In my experience, there are some, but not a lot, of suprises with test results. That is, women generally have a pretty good estimate, based on their family history and their personal history (e.g. being diagnosed under 40) whether or not they will test positively for the gene.
Even for those of us who have tested negative (and that includes me--even though I have had two primary breast cancers and was very young the first time), there are helpful bits of information. For example, I remember when the general sense was that women who had breast cancer were at higher risk for ovarian cancer. After my first diagnosis in 1993, I met with an oncology GYN surgeon who refused to do the surgery. Since the identification of the genes, we know that it is not all women who are at higher risk, but only those women who carry a gene mutation.
I have met this week with two women who have recently learned that they are gene carriers. One is trying to make a decision re whether to proceed with bilateral mastectomies or to continue with vigilant follow up. The other is most concerned with how and when to share the news with her children (short summary of my answer to that one: this is really an adult, or young adult, piece of information as a younger person surely is not going to do anything with this information. In fact, most centers will not even test people until they are at least in their mid 20s.)
This is a good summary of what we know from ABC News. I give you the start and then a link:
Breast Cancer Breakdown: Genetic Testing
Some women with a family history of breast cancer have genetic mutations that raise their
risk. And while genes are just one risk factor for the disease, knowing your status can help
you make some important decisions.
Women with mutations in the genes BRCA1 or BRCA2 are five times more likely to be
diagnosed with breast cancer, according to the National Cancer Institute. That means that
60 percent of women with a BRCA mutation will develop breast cancer in their lifetime,
compared to 12 percent of women in the general population.
But less than 1 percent of women actually have a BRCA mutation, making costly genetic
testing unnecessary for most. While the decision to get tested is a personal one, here are
some guidelines that can help you make the call:
For women who are not of Ashkenazi Jewish descent, the NCI recommends genetic
testing if you have:
Two first-degree relatives diagnosed with breast cancer, with one of them before age 51. First-degree relatives include your mother
Three or more first- or second-degree relatives diagnosed with breast cancer. Second-degree relatives include your grandmother
A combination of first- and second-degree relatives diagnosed with breast cancer or ovarian cancer;
A first-degree relative diagnosed with cancer in both breasts;
A combination of first- or second-degree relatives diagnosed with ovarian cancer;
A first- or second-degree relative diagnosed with breast and ovarian cancer;
A male relative diagnosed with breast cancer.