Endocrine Therapy for Male Breast Cancer: Rates of Toxicity and Adherence

Purpose: Most male breast cancer tumours are hormone receptor–positive; the patients therefore receive endocrine therapy. There is, however, a paucity of published data on toxicities experienced by male breast cancer patients who are prescribed endocrine therapy. In the present study, we examined rates of adherence to and toxicity from endocrine treatments in male breast cancer patients treated at a single institution. Patients and Methods: We conducted a retrospective study of male patients diagnosed with breast cancer at The Ottawa Hospital Cancer Centre during 1981–2003. Data collected included patient age, hormone receptor status, therapy adherence, self-reported toxicities, and type and duration of endocrine therapies. Results: The review located 59 cases of early-stage and metastatic male breast cancer. Median patient age was 68.0 years. Tamoxifen was given to 38 patients (64.4%), anastrozole to 8 (13.6%), and letrozole to 5 (8.5%). Of patients who received endocrine therapy, 10 (25%) received adjuvant systemic chemotherapy. Toxicity was reported by 19 patients taking tamoxifen (50%), with hot flashes being the most common complaint (18.4%). Decreased libido, weight gain, and malaise were reported by 5 patients (13.2%). Rash and erectile dysfunction were reported by 3 patients (7.9%). Increased liver enzymes, pulmonary embolism, superficial thrombophlebitis, myalgia, depression, visual blurring, and loose stools were each reported in 1 patient (2.6%). Tamoxifen therapy was discontinued secondary to toxicity in 9 patients (23.7%). Of the patients treated with anastrozole, 3 (37.5%) reported toxicity, with 1 report each of decreased libido, leg swelling, and depression (12.5%). Toxicity was reported in 2 patients taking letrozole (40%), with both reporting peripheral edema, and 1 reporting hot flashes. No patient discontinued anastrozole or letrozole because of toxicity. Conclusions: Few studies specifically report data on adherence to and toxicities from endocrine therapies in male breast cancer patients. The rate of discontinuation at our institution because of toxicity (23.7%) is similar to that reported in the female breast cancer population. Future prospective studies should explore strategies to improve adherence to endocrine therapy in this population.