Breast Cancer and the BRCA gene

Genetics play a big role in what your body does.  We know this: brown eyes, curly hair, wide hips, funny toes.  We all have those things we inherited, good and bad, which we can blame on Mom and Dad.

Many women have a higher inherited risk for breast cancer.  We don’t know how to test for many of these genes, but two we can test for are BRCA 1 and BRCA 2. BRCA genes are “tumor suppresor genes.”  In BRCA patients, there is a mutation of this gene.

People who carry a BRCA mutation have a very high risk of breast cancer. A woman’s lifetime risk of getting breast cancer is 1 in 8  if she does not have a BRCA 1 or 2. For carriers of BRCA 1 the lifetime risk of breast cancer ranges from 60 to 90 percent. For BRCA 2 the risk ranges from 30 to 85 percent (studies vary on the increased risk.)

In English, this means if you had 100 women in a room, a normal group would have 12 women who get breast cancer.  In a room of BRCA 1 women, 60- 90 of them would get breast cancer.

Who is at risk?

Women of Eastern European Jewish descent are the highest (Ashkenazi Jews).  8-10% of Asheknazi Jewish women carry the gene.  It can be passed down through your mother or your father.  Norweigan, Dutch, and Icelandic peoples also have higher incidence.

Can I lower my risk?

Studies indicate you can lower your risk if you are physically active and breastfeed.  Some things which are thought to be protective against cancer, like having kids at an early age, may not lower when you are a BRCA carrier.  And having more kids in a few studies was found to increase your risk for BRCA carriers.

What else?

BRCA carriers are at a higher risk for a second primary breast cancer (In English, that is a second totally new and exciting breast cancer, usually presenting in the other breast).  Usual rate is 10%, BRCA is more around 30%.

Also you are at higher risk for ovarian cancer. Usual rate of ovarian cancer is less than 1%, BRCA 1 women it is 20-50%, BRCA 2 is 4-20%.  Women who are BRCA positive can reduce their risk for breast cancer and ovarian cancer by removing the ovaries.  With this though comes menopause.

How can I know?

There is a simple blood test to check.  Please do this under the care and supervision of a doctor, and a genetic counselor, who can help you interpret and figure out what to do with your results.

 Should I get tested?

This is the million dollar question.  According to the US NIH National Cancer Institute, they recommend looking at the following:

• For women who are not of Ashkenazi Jewish descent:
  • two first-degree relatives (mother, daughter, or sister) diagnosed with breast cancer, one of whom was diagnosed at age 50 or younger;
  • three or more first-degree or second-degree (grandmother or aunt) relatives diagnosed with breast cancer regardless of their age at diagnosis;
  • a combination of first- and second-degree relatives diagnosed with breast cancer and ovarian cancer (one cancer type per person);
  • a first-degree relative with cancer diagnosed in both breasts (bilateral breast cancer);
  • a combination of two or more first- or second-degree relatives diagnosed with ovarian cancer regardless of age at diagnosis;
  • a first- or second-degree relative diagnosed with both breast and ovarian cancer regardless of age at diagnosis; and
  • breast cancer diagnosed in a male relative.

• For women of Ashkenazi Jewish descent:
  • any first-degree relative diagnosed with breast or ovarian cancer; and
  • two second-degree relatives on the same side of the family diagnosed with breast or ovarian cancer.