(HealthDay News) — The increased risk of breast cancer among users of hormone replacement therapy (HRT) varies by race/ethnicity, body mass index (BMI), and breast density, according to a study published online Sept. 3 in the Journal of the National Cancer Institute.
Ningqi Hou, Ph.D., from the University of Chicago, and colleagues examined the impact of patient factors on the correlation between HRT and breast cancer risk using data from 1,642,824 screening mammograms from the Breast Cancer Surveillance Consortium, a longitudinal registry of mammography screening in the United States, with 9,300 breast cancer cases in postmenopausal women aged 45 years or older.
The researchers found that there was a significant, more than 20 percent increased risk of breast cancer associated with HRT use in white (odds ratio [OR], 1.21), Asian (OR, 1.58), and Hispanic women (OR, 1.35), but not black women (OR, 0.91). Compared with nonusers, HRT users with low/normal BMI and extremely dense breasts had the highest breast cancer risk (OR, 1.49). No excess risk was associated with HRT use in overweight/obese women with less-dense breasts (adjusted ORs, 0.96 to 1.03).
“The impact of HRT use on breast cancer risk varies according to race/ethnicity, BMI, and breast density,” the authors write. “This risk stratification could help in advising HRT use for the relief of menopausal symptoms.”