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, that 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 percent 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.
If one of your aunts did carry the BRCA gene, your father had as high as a 50 percent chance of having inherited the same mutation from the same parent as his sister did. If so, you would have half of your father’s risk of having inherited the BRCA mutation. So the highest likelihood that your daughter has inherited this BRCA breast cancer vulnerability mutation would be 12.5 percent. Is that a big enough risk to merit DNA testing? Your daughter would have to decide that for herself after careful genetic counseling about the risks and benefits of testing.
Parents don’t choose to pass on a damaged gene. Even so, guilt and shame get involved. And children often can’t help but get angry. Some blame the parent for passing on a deleterious gene — along with everything else that goes wrong! Learning that you’re vulnerable to a life-threatening problem is difficult for anyone. Reactions range from a positive, powerful surge of resolve to sad, even dangerously depressed, inertia.
So it’s important that you and your daughter proceed carefully and thoughtfully. Besides checking to see whether your aunts’ medical records are available, you might contact relatives to see if anyone else has been tested. Depending on what you find out, and other factors, you may want to get careful breast exams by clinicians. Next, you can get a personalized cancer-risk assessment by certified genetic counselors or by physicians with training in medical genetics.
People with BRCA mutations can take action to reduce their cancer risk. The choices depend on your sex, age and stage in family planning. Some women may choose more frequent monitoring by mammography, ultrasound, or MRI. You or your father might want to get tested first, hoping that the BRCA genetic mutation is missing from your DNA.
Dr. Susan P. Pauker, Harvard Vanguard Medical Associates, Harvard Health Letter editorial board
