Mammographic density changes during different postmenopausal hormone replacement therapies

Objective: To determine the degree of change in mammographic breast densities during different types of postmenopausal hormone replacement therapies. Design: A retrospective study. Setting: Ege University Hospital. Patient(s): The mammographies of 216 women on various postmenopausal hormone replacement therapies were evaluated. Intervention(s): Estrogen alone (n = 76) or estrogen in cyclic (n = 44) or continuous (n = 61) combination with progestin or tibolone-only (n = 35) replacement therapies were used. Mammographic density was quantified according to the Wolfe classification in patients with different hormone replacement regimens. Main Outcome Measure(s): Mammographic density changes were interpreted. Result(s): An increase in mammographic density was much more common among women receiving continuous combination hormone replacement therapy 31.1% (19 of 61) than among those receiving estrogen-only 3.9% (3 of 76) treatment. There were no significant mammographic breast density changes among women receiving cyclic continuous combination hormone replacement therapy or tibolone-only treatment. The increase in density was apparent already at first visit after the start of hormone replacement therapy. In continuous combined postmenopausal hormone replacement therapy with norethisterone acetate, the increase in mammographic density was 34.1% (15 of 44), followed by medroxyprogesterone acetate 23.5% (4 of 17). Conclusion(s): Our findings show that mammographic breast density changes related to postmenopausal hormone replacement therapy are dependent on the selected hormone regimen. The continuous administration of the progestin component of the combined-hormone replacement therapy seems to effect the breast density most.