The effects of hormonal replacement therapy (HRT) on mammographic breast density and abnormal mammograms prompting further investigation.

Abstract

8 Background: Mammographic density has been associated with higher risk of breast cancer and lower sensitivity. HRT has been implicated with increased density and is also a risk factor. The relationship between HRT, breast density, and mammographic findings requiring investigation has not been fully investigated. We aimed at analyzing this correlation. Methods: 2,758 consecutive, single-center screening mammograms performed during 1 year were analyzed. Mammograms were supplemented by ultrasound. Density was measured by a semiquantitative, 5-grade scale, and grouped into low (1-3) (LDM) and high density (4-5) (HDM). Demographic and obstetric data, personal and family history of breast cancer, and the use of HRT were entered into database. These parameters were correlated with breast density and any abnormality detected. Univariate and multivariate analysis as well as multivariate logistic regression were performed on SAS 9.2. Results: Mean overall age was 48 (SD = 10.8, range 27-78), mean ages of LDM and HDM groups were 59 ± 10.5 and 50.9 ± 9.3 respectively (p = 0.001). Of 2,758 tests, 2,094 (76%) were LDM and 664 (24%) were HDM. 1,962 women (71%) were postmenopausal and 592 (30%) were on HRT. A difference in density between pre- and postmenopausal women was observed (p = 0.0001). HRT was not associated with higher rate of HDM (18%, n = 105/582) vs.15% n = 211/1370 (p = n.s) without HRT. Abnormality was more likely in postmenopausal HRT-less (52% n = 711/1370) vs. (30% n = 226/582) HRT (p = 0.0001) including solid lump (p = 0.0001), tissue irregularity (p = 0.016) and calcifications (p = 0.0005). Menopause was associated with 48% of any finding vs. 41.4% in pre-menopause women (p = 0.0017). 104 malignant lesions were found in 267 with mammographic findings prompting histological assessment. HRT was associated with lower incidence (28%) of malignancy compared to 50% without HRT. Conclusions: HRT was not associated with increased density nor with higher risk of malignancy; moreover, a lower rate of mammographic abnormality was noted. Albeit further studies are required, the results of this study do not support the notion that HRT increases the likelihood of malignancy or affects breast density.