Hematologic and other
Gynecomastia prevention
A brief breast dose that prevents painful male breast enlargement caused by prostate cancer hormone therapy.
Definition
Gynecomastia is benign enlargement of male breast glandular tissue, presenting as painful, tender swelling beneath the areola. In prostate cancer management, antiandrogens such as bicalutamide cause gynecomastia in a large majority of patients when given without prevention, creating embarrassment and pain that can undermine adherence to therapy. Estrogen-based prostate treatments carry the same problem.
How radiation treats it
Prophylactic breast irradiation given before or at the start of antiandrogen therapy suppresses the glandular epithelium and local hormone sensitivity of the breast tissue so that the hormonal stimulus cannot trigger proliferation. A short course of low-dose radiation prevents the development of gynecomastia and breast pain in most patients, whereas radiation is far less effective once tenderness and tissue changes have already developed.
Side effects
- Mild, transient nipple or areolar irritation and erythema are the main acute effects.
- Temporary skin darkening around the nipple.
- Long-term effects at these doses are essentially absent; the small theoretical chest-wall risk is dwarfed by the morbidity of the gynecomastia being prevented.
Simulation process
The patient is positioned supine with arms above the head or akimbo. No CT simulation is needed — the target is defined clinically by palpation: both breasts (or the breast buds) are marked with a small margin around the areola. Kilovoltage photons or 6–9 MeV electrons are planned with bolus, and lead shielding protects the surrounding chest. The fields are small, typically 6–8 cm circles centered on the breast bud.
Treatment process
A common regimen is 12 Gy in two fractions of 6 Gy delivered days apart, or 10–15 Gy in 3–5 fractions, completed before the antiandrogen starts or within the first weeks. Each fraction takes minutes using superficial beams. Tamoxifen is an alternative prevention strategy; radiation is chosen for patients who cannot take it or prefer local treatment.
Key takeaways for students
- Preventive, not therapeutic — radiation works only before glandular proliferation begins.
- 12 Gy in two fractions is a typical US prophylactic scheme.
- Bilateral small electron fields with bolus over the breast buds.