[Influence of size and duration of gynecomastia on its response to treatment with tamoxifen]

Gynecomastia is treated when it is painful, there are psychosocial repercussions or it does not revert in less than two years. It is treated with the antiestrogenic drug tamoxifen, but there are doubts about its effectiveness in high volume gynecomastias or in those lasting more than two years.

To assess the effectiveness and safety of tamoxifen for gynecomastia and the influence of its volume and duration on the response to treatment.

Forty three patients with gynecomastia, aged 12 to 62 years, were studied. Twenty seven patients had a pubertal physiological gynecomastia, in eight it was caused by medications, in four it was secondary to hypogonadism, in three it was idiopathic and in one it was due to toxic exposure. Twenty patients had mastodynia and in 33, gynecomastia had a diameter over 4 cm. It lasted less than two years in 30 patients, more than two years in nine and four did not recall its duration. All were treated with tamoxifen 20 mg/day for 6 months. A follow up evaluation was performed at three and six months of treatment.

Mastodynia disappeared in all patients at three months. At six months gynecomastia disappeared in 26 patients (62%), but relapsed in 27%. All gynecomastias caused by drugs with antiandrogen activity disappeared. Fifty two percent of gynecomastias over 4 cm and 90% of those of less than 4 cm in diameter disappeared (p<0.05). Fifty six percent of gynecomastias lasting more than two years and 70% of those of a shorter duration disappeared (p=NS). Two patients had diarrhea or flushes associated to the therapy.

Tamoxifen is safe and effective for the treatment of gynecomastia. Larger lesions have a lower response to treatment.