Prophylactic breast bud radiotherapy is used to prevent gynaecomastia and mastalgia in patients with prostate cancer who are being treated with antiandrogen and oestrogen therapy. Here a case is presented of a patient who developed soft-tissue sarcoma of the breast subsequent to breast bud radiotherapy prior to bicalutamide hormone treatment. Bicalutamide is often prescribed for younger men in the adjuvant setting or as monotherapy for locally advanced disease. The data regarding the efficacy of prophylactic breast bud radiotherapy is reviewed, and it is proposed that alternative therapies should be considered such as tamoxifen.