Hidden Genetic Links to Breast Cancer
For a long time, doctors have known that breast cancer runs in families. This information serves as motivation for thousands of women to schedule regular mammograms, especially if they are aware that breast cancer runs in their family. But is it possible for this heightened risk to be passed down from one generation to the next without anyone in the family knowing it? According to a recent study in the Journal of the American Medical Association, it is.
Dr. Jeffrey Weitzel, a professor of oncology and population science at City of Hope Cancer Center in Duarte, Calif. and the man behind the study, says genetic links to breast cancer may be hidden in some families. "Because some families are so small and with so few female relatives," one article reads, "patients sometimes suspect their breast cancer is sporadic, occurring with no apparent familial link." In other words, a woman with breast cancer who has very few aunts and older sisters may think the disease came from out of nowhere, but doctors now believe the risk may be hidden on the father's side.
There are two genes passed down from generation to generation which present an increased risk for breast cancer if either of the two are mutated. These genes, called BRCA1 and BRCA2, are described as tumor suppressor genes. When mutations alter or inactivate the function of these genes, cancer is more likely to develop.
Half of genetic breast cancers are inherited from a woman's father, not her mother. In fact, researchers suggest they can be transmitted from grandfather to father to daughter just as easily as they can be passed on from grandmother to mother to daughter. But unless a woman's father has female relatives with breast cancer, the defective gene may be passed down silently, without causing cancer.
Dr. Weitzel says many people reject the idea that the father can be the contributor. But according to his study, fathers are just as important as mothers when it comes to determining risk. "A patient can be blinded as to what's happening on the paternal side," he says. "If a man has no sisters and his daughter develops breast cancer, not only is the cancer risk hidden, but the patient also misses a key opportunity for genetic screening."
Genetic screening is important for those with a family history of breast cancer because it can give doctors vital information about their patients' risks and implications for future generations. One major problem, according to Dr. Weitzel, is that doctors often overlook the genetic risk from the father's side of the family.
In addition to raising awareness about the possibility of hidden genetic links to breast cancer, the study also provides evidence to support the idea that genetic testing should be covered by insurance companies. Current insurance guidelines dictate reimbursement for genetic screening based on obvious patterns of inheritance. This kind of testing can cost up to $3,000.
Dr. Noah Kauff, a cancer geneticist at Memorial Sloan-Kettering Cancer Center in New York, supports Dr. Weitzel's stance on the current insurance guidelines. In an editorial, he wrote that the study "allows physicians and patients to make an argument to insurance carriers that, although there's not a family history of breast cancer, it's still reasonable to test and it should be a covered benefit."
Genetic testing can help a woman with breast cancer decide what to do next. A woman who has a BRCA gene mutation has a four times greater risk of developing breast cancer and a 10 times greater risk of ovarian cancer than does a woman with breast cancer who has no BRCA gene mutation. Some women with a family history of breast cancer choose to undergo genetic testing so they can decide whether to reduce their cancer risk by removing their ovaries and breasts before any cancer appears.
Testing the genes of more women would cost more money, of course, but Dr. Weitzel says it wouldn't significantly increase overall healthcare costs and it would prevent cancer in numerous cases. He hopes the study's findings will put pressure on insurance companies to change the guidelines to determine coverage for genetic testing.