What's my risk?
Genetic testing in cancer-prone families
A genetic puzzle: Linda Manning's father, Ed Klevans, and mother, Deb, (right) both developed breast cancer, but tests showed neither carries a mutant breast cancer gene. Manning and her daughter, Sienna, most likely didn't inherit a mutation, yet Linda is considered at higher-than-average risk.
When it comes to cancer, all women are not created equal. Some — relatively few, fortunately — are destined to have unusually high risks of breast and gynecologic cancers because of inherited genes, ethnic ancestry, or family history.
It has long been known that cancer susceptibility can travel within families over many generations. What's new in the last 10 years is the discovery of mutant genes that can create a high risk of breast and ovarian cancer in families. Researchers isolated the BRCA1 and BRCA2 genes in 1994 and 1995. In a mutant form, these genes can raise lifetime breast cancer risk to as high as 85 percent, and the chance of developing ovarian cancer to as high as 50 percent.
Before the genes were found, doctors had no way of telling an individual woman in a high-risk family whether she herself had inherited such a risk. Genetic testing enables a woman to find out. But testing — a sort of genetic crystal ball — has created new dilemmas: Does a woman want to have this knowledge? How effective are risk-reduction measures? And what protections are there for her genetic privacy?
To provide risk assessment, clinical care, and psychological support, the Friends of Dana-Farber Cancer Risk and Prevention Clinic opened in 1992. Director Judy Garber, MD, says it was one of the first multidisciplinary cancer risk clinics in the country. Researchers work with patients facing higher rates for rare genetic cancer disorders, and they investigate ways for patients to lower their elevated risk.
Most women have about 1 in 600 odds of inheriting a mutant breast cancer gene, but one population group suffers a disproportionate burden: women of Ashkenazi (Eastern European) Jewish descent, whose risk is about 1 in 40.
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