BRCA

[sister 3]

My sister was diagnosed with a breast adenocarcinoma recently.  We have a family history of ovarian cancer; my mother dying at the age of 47.  Both of us had prophylactic oophorectomy/hysterectomy, mine was done 10 years ago at 36.  I was on HRT until this summer, am now off of estrogen.
My internist wants me to have the BRCA testing done.  I understand this test to be less than 100% with it's prediction of breast cancer.  Can you give me information?

[CCF-RN,MSN-JS]

Dear sister 3, Usually genetic testing would start with a family member with known breast or ovarian cancer.  If your sister, for example, were to be tested and found to be BRCA positive, then testing you might be indicated.  You might find it helpful nonetheless to discuss your risk with a genetic counselor, who could determine your risk and make good recommendations (including the possibility of BRCA testing) for surveillance.  If the person is a carrier of the BRCA gene the probability of developing breast or ovarian cancer in one's lifetime is significantly increased.  However, the timing of such a development is unknown, and there is a possibility that cancer may not develop in all cases.  

[surgeon]

what it does is test to see if you have a particular gene that is associated with a form of breast cancer (and ovarian). Most women who get breast cancer don't have the gene, so not having the gene does not mean you won't get breast cancer, but it means your risk is the same as that of most other women. If you do have the gene, then it means your risk of getting breast cancer is extremely high. Which then raises the question of what your response would be to that knowledge. There really are only two basic options: having very careful screening, which presumably you'd be doing anyway, or having your breasts removed. If you think that's what you'd do, then it makes sense to be tested. Being off estrogen and without ovaries as you are in theory lowers your risk somewhat.