White and Hispanic women who receive hormone replacement therapy are far more likely than women of other races to develop breast cancer, according to a new study published in the Journal of the National Cancer Institute.
 

Although past studies have linked HRT use to breast cancer, the new study by University of Chicago researchers provides greater clarity on the variability of risk based on race.
 

Lead researcher Ningqi Hou said the findings may help doctors determine which patients are more likely to benefit from HRT to relieve postmenopausal symptoms and which face risks that outweigh such benefits.

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"Black women, obese women, and women with breast tissue composed largely of fat may benefit from HRT use with minimal excess breast cancer risk," Hou said, adding that more studies are needed to identify the risks and benefits of HRT for postmenopausal women.
 

For the study, researchers analyzed more than 1.6 million mammograms, including those of 9,300 breast cancer patients, contained in a U.S. registry of mammography screening. They also tracked HRT use by race/ethnicity, age, BMI, and breast density.
 

The results showed HRT was associated with a 20 percent increased risk in breast cancer among white women and Hispanic women, but not black women. HRT use was more strongly associated with breast cancer risk in women with low or normal BMI. And those with denser breasts had an increased likelihood of breast cancer among those who reported HRT use.
 

"Ultimately, efforts that improve risk stratification, whether made through improved risk models or through measuring valid intermediate biomarkers such as breast density, will inform appropriate use of not only HRT, but also other medications, including chemopreventive drugs," said Mary Beth Terry and Parisa Tehranifar, from Columbia University, in an editorial accompanying the study.