The risk of developing breast cancer due to taking hormone replacement therapy appears to be the same for women with a family history of the disease and without a family history, a University of Rochester Medical Center study concluded.
The study, published online this week in the journal Epidemiology, adds to the evolving picture of what factors, either alone or in combination, boost breast cancer risk among postmenopausal women. It also refutes the notion, held by many in the medical community, that a familial predisposition to breast cancer enhances the carcinogenic effects of estrogen.
"Although we know that family history is a risk factor, we don't know yet what it is about family history that conveys the risk," said Robert E. Gramling, M.D., D.Sc., assistant professor of Family Medicine and of Community and Preventive Medicine at URMC. "Some have proposed that it might be an increased sensitivity to estrogen, but our data did not support that notion. In fact, this study suggests the causal pathway based on family history is probably not estrogen sensitivity."
Researchers analyzed data from the Women's Health Initiative randomized trial, which followed 16,608 postmenopausal women, ages 50 to 79, who took hormone replacement therapy (HRT) or a placebo pill between 1993 and 2002. Among the participants, 349 cases of invasive breast cancer occurred during a mean follow-up period of 5.6 years.
Gramling divided the data into subgroups and studied the direct interaction between the contributions that the two risk factors (HRT and family history) had on breast cancer risk among postmenopausal women. The results showed only a negligible degree of interaction, suggesting that HRT conveys no greater breast cancer risk to women with, versus without, a first-degree family history of breast cancer (i.e. breast cancer in a mother, sister or daughter).
The study does have limitations, the authors noted. First, the wo
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| Contact: Leslie Orr Leslie_Orr@urmc.rochester.edu 585-275-5774 University of Rochester Medical Center Source:Eurekalert |