By the way, doctor: Should my daughter get a breast cancer gene test?
Q. Both of my father's sisters died of breast cancer years ago, one before menopause, the other just after. I have an 18-year-old daughter. I've been wondering if I should talk to her about getting tested for the breast cancer gene. I'm the dad.
A. Breast cancer is caused by a combination of many environmental and genetic factors. We don't yet know most of the genetic changes, or mutations, which cause it. However, we can test for two of them. These BRCA — short for breast cancer — mutations are inherited in an autosomal dominant pattern, which means that if men or women have inherited the mutation, there's a 50% chance of passing the genetic change on to their sons or daughters. Not everyone who has inherited the BRCA-1 mutation will develop breast cancer, but the risk is greater than for the general population. BRCA-2 mutations also increase the risk for getting ovarian cancer. Breast cancer is rare in men, but if a man has the mutation, he's just as likely as a woman to pass this vulnerability to half of his children, male and female.
Both of your aunts died of the disease when they were fairly young. Have you explored whether you could get their medical records? Absence of BRCA mutations doesn't rule out all genetic inheritance factors: perhaps they had an as-yet undiscovered mutation that confers added risk. But from what you have written, they are the only two cases in the family. If there are no other associated cancers, such as pancreatic or ovarian, it's possible that there is no mutation in your family — and no increased breast cancer risk.