Approximately 2000 American men are diagnosed with breast cancer every year. Limited data are available evaluating toxicity of antihormonal treatments in male breast cancer patients.

We reviewed male breast cancer patients evaluated at our institution (1999-2009). Of 126 patients, 64 met the following inclusion criteria: stage I-III, treated with tamoxifen, at least one follow-up visit after starting tamoxifen. A descriptive analysis of toxic effects was carried out on these 64 patients.

Median follow-up from start of tamoxifen therapy was 3.9 years (range 0.3-19.4 years). Median age at diagnosis was 61 years (range 30-79 years). Breakdown by stage: 29.7% (n = 19) stage I, 54.7% (n = 35) stage II, and 15.6% (n = 10) stage III. Thirty-four (53%) patients experienced one or more toxicity while taking tamoxifen. Most common toxic effects are weight gain (14 patients, 22%) and sexual dysfunction (14 patients, 22%). Thirteen (20.3%) patients discontinued tamoxifen due to toxicity: one ocular, one leg cramps, two neurocognitive deficits, two bone pain, three sexual dysfunction, and four thromboembolic events.

To our knowledge, this is the largest study examining tamoxifen-related toxic effects among male breast cancer patients. Among male patients, there is a high rate of discontinuation of tamoxifen. Prospective studies of antihormonal agents in male breast cancer are warranted.