Factors That Influence Changes in Mammographic Density With Postmenopausal Hormone Therapy

SummaryObjectiveTo evaluate the relationship between mammographic density and clinical factors in postmenopausal women using hormone therapy (HT).Materials and MethodsRetrospective study of 467 postmenopausal women who received continuous estrogen or estrogen-progestin HT and had regular mammography between 1994 and 2001. A detailed clinical history was recorded, including age at start of HT, age at menopause, years from onset of menopause to start of HT, body mass index (BMI), and duration and regimens of HT.ResultsAfter adjustment for the effects of other variables, age at the start of HT and BMI were inversely associated with breast density (p = 0.0025 and < 0.001, respectively). In contrast, duration of HT was positively related to mammographic density (p<0.001). Although the mean density was significantly increased after 4 years of HT in women receiving combined HT compared with those using estrogen alone, after adjustment for the effects of other variables, the correlation between mammographic density and regimen of HT (combined HT vs. estrogen alone) did not reach the significance level of 0.05.ConclusionHigher mammographic density was associated with longer use of HT, especially in younger post-menopausal women and those with lower BMI.