Side Effect: Swelling of breast tissue (gynecomastia)

Swelling of breast tissue, also known as gynecomastia, is a condition characterized by the development of glandular breast tissue, resulting in breast enlargement.

It is caused by an imbalance of estrogen and testosterone hormones in the body, where there is an increase in estrogen and a decrease in testosterone.

The appearance of gynecomastia typically presents as a palpable, firm, mass under the nipple-areolar complex, with or without tenderness. Breast tissue may be affected in both breasts or just one and the increase in breast tissue size can range from small to large.

In patients with cancer, gynecomastia occurs more often in those who undergo hormonal therapy.

• Men with prostate cancer who are treated with androgen deprivation therapy (ADT), such as bicalutamide (Casodex®) or enzalutamide (Xtandi®), may experience gynecomastia as a side effect of the treatment.
• More selective ADT therapies like apalutamide (Erleada®) are not known to cause gynecomastia.

• Prevention of gynecomastia in in men with prostate cancer may involve the use of selective estrogen receptor modulators (SERMs), such as tamoxifen (Nolvadex®).
• If tamoxifen is not effective or cannot be used, and the gynecomastia is bothersome, other ADT therapies that don’t cause gynecomastia or alternative treatments to ADT may be considered.

• For mild cases of gynecomastia, observation alone may be appropriate.
• More severe cases may require additional therapy such as tamoxifen or in some cases, radiation.
• Surgery might also be a treatment option but is typically only used for those patients where other treatments have failed.