Study: Family history does not affect risk of breast cancer with HRT

May 26, 2009

test-tubes

image by Hey Paul

Scientists at University of Rochester Medical Center have published a study in the journal Epidemiology which shows that the risk of developing breast cancer due to taking hormone replacement therapy appears to be the same, whether or not a woman has a family history of the disease. Family history and hormone replacement therapy have each been established as risk factors for postmenopausal women. Gramling’s study focused on whether interaction between the two raised the risk.

“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.” (If family history increased risk of breast cancer by raising estrogen sensitivity, then women with a family history of breast cancer would have had significantly more cancer when using HRT).

Researchers analyzed information from a previous trial that took place between 1993 and 2002. Gramling divided the data into subgroups and studied the direct interaction between the contributions that 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 (mother, sister, or daughter) family history of breast cancer.  Of course, the study did not say that HRT does not raise the risk of cancer; it merely said that HRT does not raise the risk of cancer more for those with a familial tendency toward breast cancer then for those without the family history. 

The study does have limitations, the authors noted. First, the women had a short period of exposure to hormone treatment and a short follow-up period. It is possible that longer exposure to HRT would have generated different results. Also, researchers asked women about family history of breast cancer only at the start of the WHI study. Finally, the majority of women who enrolled in the WHI trial represented a more educated and somewhat healthier population, and it is unknown how this might have influenced any interaction between hormone therapy and family history.

Gramling believes his research is significant, especially since the earlier study raised fears of HRT increasing the risk of breast cancer. “The decision to use hormonal therapy, even for a short period of time, is very difficult for many women,” Gramling said. “We hope our data will provide postmenopausal women and their physicians more evidence to consider when weighing the risks versus benefits.”

Reference: University of Rochester Medical Center (2009, May 25). HRT-breast Cancer Risk Stays Same, Regardless Of Family History, Study Finds. ScienceDaily. Retrieved May 25, 2009, from http://www.sciencedaily.com­ /releases/2009/05/090519134715.htm

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