Tamoxifen is an off-label option to treat men for
breast cancer,
infertility, and idiopathic
gynecomastia. Lately,
tamoxifen has been proposed as a treatment to prevent
gynecomastia in
prostate cancer patients receiving
antiandrogen therapy. We reviewed the adverse events (AEs) reported in studies of men prescribed
tamoxifen for these conditions to better understand its side-effect profile. We searched PubMed for randomized controlled trials (RCTs) that included safety data of
tamoxifen treatment in men with
prostate cancer,
breast cancer,
infertility, and idiopathic
gynecomastia. Non-RCTs were also reviewed. The results demonstrate that the AE profile in
tamoxifen-treated male populations varied. Excluding breast events, gastrointestinal, and cardiovascular problems were the most commonly reported AEs in
prostate cancer patients, whereas more
psychiatric disorders were reported in
male breast cancer patients. Few AEs have been documented in men receiving
tamoxifen for
infertility and idiopathic
gynecomastia. Less than 5% of men withdrew from
tamoxifen therapy because of toxicity. This suggests that for most men,
tamoxifen is well-tolerated. Of those who discontinued
tamoxifen, the majority were
male breast cancer patients, and cardiovascular events were the most common reason for stopping
tamoxifen treatment. Unfortunately, in many cases, the reasons for withdrawing
tamoxifen were unspecified. Based on the available evidence,
tamoxifen's AE profile appears to vary depending upon which male population is treated. Also, the frequency at which AEs occur varies - less AEs in men with
infertility and idiopathic
gynecomastia compared to men with
prostate cancer or
breast cancer. Long-term studies that rigorously document the side-effect profile of
tamoxifen in men are lacking.