Role of tamoxifen in idiopathic gynecomastia: A 10-year prospective cohort study.

BACKGROUND: Idiopathic gynecomastia is a benign breast disorder characterized by overdevelopment of male breast tissue. It can cause discomfort and concern, resulting in patients seeking diagnosis and treatment. We aimed to evaluate the efficacy of tamoxifen therapy in resolving this condition. METHODS: We undertook a prospective cohort study of all male patients who presented to our breast clinic, were diagnosed with primary gynecomastia, and were treated with a trial of tamoxifen 10 mg daily therapy, over a 10-year period from October 2004 to October 2015. All patients underwent routine investigations to exclude secondary causes of gynecomastia. The end point of interest was the complete resolution of gynecomastia. RESULTS: We included 81 patients in this study. The mean age was 42.8 years (SD 19.5 years). Of these, 28.4% were bilateral gynecomastia and 71.6% were unilateral. The majority (87.7%) of cases presented with accompanying mastalgia. Following treatment, 90.1% (n = 73) had a complete response of their gynecomastia with tamoxifen therapy. Only eight patients did not have a complete resolution following tamoxifen therapy, of which two underwent subsequent surgical resection of their symptomatic gynecomastia. CONCLUSION: Our study is the largest to date examining the role of tamoxifen in idiopathic gynecomastia, and our results show approximately nine in every 10 men treated with tamoxifen therapy had successful resolution of their symptoms. We support its use for idiopathic gynecomastia in eligible men following the careful discussion of its risks and benefits.