Women From Small Families May Not Be Properly Screened for Breast Cancer Mutations
Women are told they face a higher risk of inherited breast or ovarian cancer if they have close female relatives who had those cancers before age 50. But many women don't have enough female relatives to make that a reliable gauge, according to a new study in the Journal of the American Medical Association. As a result, many women with genes predisposing them to breast and ovarian cancer may not be getting the genetic testing they need to find that out and understand the risk they face.
"In order to have a family history, you have to have family," says Jeffrey Weitzel, director of the department of clinical cancer genetics with the City of Hope Cancer Center in Duarte, Calif., who led the study. He is concerned that women are being steered away from genetic testing, thus missing out on appropriate treatment.
To find out, Weitzel and his colleagues looked at the records of 306 women who had breast cancer before age 50, but no first- or second-degree relatives with breast or ovarian cancers. Almost 10 percent of them had BRCA gene mutations.
The women with a "limited" family structure, meaning fewer than two close female relatives who lived past age 45, were more likely to have BRCA gene mutations, 13.7 percent versus 5.2 percent for those with more female relatives. In the smaller families, the commonly used screening question, "Do you have any relatives with breast or ovarian cancer?" was less useful in predicting risk.
The study also points out the limitations in computer models commonly used to predict a woman's cancer risk based on family history. The three models commonly used to compute breast cancer risk underestimated the likelihood of a genetic mutation in a woman with a limited family and overestimated in families with more female relatives.
Women should be aware that half of hereditary breast cancer is passed on from the father's side, Weitzel says, and try to find out as much as they can about health history of women on both sides of the family tree. The good news is that closer monitoring or risk-reduction surgery can significantly improve the odds of beating or avoiding cancer for women with these mutations, making appropriate screening all the more important.
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