The Effect of Transdermal Testosterone on Mammographic Density in Postmenopausal Women Not Receiving Systemic Estrogen Therapy

Context: Greater mammographic density is associated with increased breast cancer risk and reduced diagnostic mammographic sensitivity and may be seen with estrogen/progestin therapy (EPT). The effects of testosterone therapy on mammographic density in postmenopausal women not on EPT are not known. Objective: Our objective was to compare effects of two doses of the testosterone transdermal patch (TTP) with placebo in postmenopausal women without concomitant EPT on mammographic density over 52 wk. Design: We conducted a randomized, double-blind, placebo-controlled, parallel-group, multinational trial. Patients: Patients included 279 postmenopausal women participating in a testosterone and sexual function study with paired mammograms for baseline and 52 wk/exit. Interventions: Patients were randomized to placebo, TTP 150 μg/d, or TTP 300 μg/d, stratified by menopause type (natural or surgical). Main Outcome Measures: Change from baseline to wk 52 in the percentage of dense tissue (PD) on digital mammograms. Results: A total of 250 women with paired mammograms for study baseline and wk 52 were included in the primary analysis. Mean age was 54.6 yr, baseline body mass index was 27.5 kg/m2, and 78% were naturally menopausal. There were no baseline differences between groups. Mean changes from baseline (±sem) in PD for placebo, TTP 150 μg/d and TTP 300 μg/d were small (0.05 ± 0.16, 0.06 ± 0.19, and 0.21 ± 0.17%) and not significantly different. There were no statistically significant differences from placebo for total dense or nondense area and no significant relationships between hormone levels and PD after adjustment for body mass index. Conclusion: TTP therapy over 52 wk appears to have no significant effect on digitally quantified absolute or percent dense mammographic area in postmenopausal women not using EPT. Transdermal testosterone patch therapy has no significant effect on digitally quantified absolute or percent dense mammographic area.