Low rate of clinician-scored gynecomastia induced by 6 months of combined androgen blockade in a randomized trial: Implications for prophylactic breast irradiation.

PURPOSE: To determine the incidence and predictors of clinician-scored gynecomastia induced by 6 months of combined androgen blockade (CAB) in a randomized trial.

METHODS

We studied 94 men with intermediate or high-risk prostate cancer randomized to radiation plus 6 months of neoadjuvant CAB consisting of a gonadotropin-releasing hormone agonist and antiandrogen (flutamide). Patients were assessed for breast symptoms monthly as per protocol. Patients reporting breast tenderness or enlargement were then examined shirtless.

RESULTS

Median age at entry was 72.1 years. While 52 patients (55.3%) reported either breast tenderness or enlargement, only 9 patients (9.6%) were scored as having gynecomastia when examined shirtless by a single clinician. Four patients received radiation for self-reported breast tenderness or enlargement without clinician-scored gynecomastia. If these 4 had not been radiated, the total incidence of clinician-scored gynecomastia may have been as high as 13 of 94 (13.8%). No patient variable, such as age, body-mass index, and Adult Comorbidity Evaluation-27 score, or discontinuation of the antiandrogen, was associated with the development of gynecomastia.

CONCLUSIONS

While many patients self-reported breast tenderness or enlargement with short-course CAB, the incidence of breast enlargement noticeable to an examiner when the patient was shirtless was less than 15%, which is much lower than the 60% to 80% rates typically reported with antiandrogen monotherapy. Given that the long-term risks of prophylactic breast irradiation are not well characterized, these data suggest that prophylactic breast irradiation may not be as necessary in men receiving short-course CAB.