Digitized assessment of mammographic breast density in patients who received low-dose intrauterine levonorgestrel in continuous combination with oral estradiol valerate: a pilot study.

OBJECTIVE To perform a pilot study of the effects on the breast by low-dose intrauterine progestogen combined with estrogen. DESIGN A prospective pilot study. SETTING University hospital. PATIENT(S) Twenty postmenopausal women without any previous breast disorder. INTERVENTION(S) Women were treated with a low-dose intrauterine system releasing 20 microg/24 hours of levonorgestrel in continuous combination with 2 mg of oral E2 valerate. The effects on mammographic breast density, breast cell proliferation, and hormonal levels were followed for 18 months. MAIN OUTCOME MEASURE(S) Change in mammographic breast density and breast cell proliferation. Correlations with levels of hormones, growth factors, and binding proteins. RESULT(S) Three women showed an apparent increase in density. For the remaining 17 women the changes were only a few percent. Digitized assessment of density showed strong correlations with visual classification scales (rs = 0.96-0.97). There was no increase in proliferation as expressed by the percentage of MIB-1-positive breast cells in fine-needle aspiration biopsies. Increase in breast density displayed a positive correlation with patients age (rs = 0.52) and an inverse relationship with levels of E2 (rs = -0.50) and free T (rs = -0.50). CONCLUSION(S) Low-dose intrauterine administration progestogen may develop into an attractive alternative for hormonal therapy in postmenopausal women as endometrial protection may be achieved at very low systemic levels.