Tamoxifen, an anti-estrogen agent used in the treatment of breast cancer, appears to suppress gynecomastia and breast pain in men undergoing androgen-suppression therapy for prostate cancer.

Researchers conducted a meta-analysis of four independent clinical trials focusing on the use of tamoxifen for the management of breast events during treatment for prostate cancer. All four studies provided data on the prevention of gynecomastia and breast pain by tamoxifen 10 mg or 20 mg daily.

Compared with untreated controls, tamoxifen significantly reduced the risks of suffering from gynecomastia and breast pain at 3, 6, 9, and 12 months of treatment. Overall, tamoxifen therapy reduced breast symptoms more effectively than did the selective aromatase inhibitor anastrozole or radiotherapy.

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All four studies presented data on adverse events associated with tamoxifen use compared with no additional therapy or placebo. There were no significant differences for any adverse events. Two of the studies reported fewer adverse events for tamoxifen 20 mg/day than for anastrozole 1 mg/day. Radiotherapy significantly increased the risk of suffering from nipple erythema and from skin irritation compared with tamoxifen 10 mg/day, but not the risk of other adverse events.

“The currently available evidence suggests good efficacy of tamoxifen for the prevention and treatment of breast events induced by nonsteroidal antiandrogens,” concluded the investigators in BMC Medicine (2012;10:96). However, they cautioned, because none of the studies presented long-term follow-up data, the impact of tamoxifen therapy on long-term adverse events, disease progression, survival, and other outcomes remains unclear and should be considered when prescribing this treatment.