{"entity":{"id":"gynaecomastia","kind":"term","name":"Gynaecomastia","aka":["breast swelling in men","breast tenderness on hormone therapy"],"tldr":"Swelling and tenderness of the chest caused by hormone treatment, ranging from mild sensitivity to noticeable breasts.","summary":"It is most associated with anti-androgen tablets taken on their own. NICE NG131 says that for people starting long-term bicalutamide monotherapy of longer than 6 months, prophylactic radiotherapy to both breast buds should be offered within the first month, as a single fraction of 8 Gy using orthovoltage or electron beam, and that weekly tamoxifen can be considered if radiotherapy does not prevent it.","asOf":"2026-09-25","links":[{"label":"NICE NG131: prostate cancer, diagnosis and management","url":"https://www.nice.org.uk/guidance/ng131/chapter/Recommendations"},{"label":"Prostate Cancer UK: how hormone therapy affects you","url":"https://prostatecanceruk.org/prostate-information-and-support/living-with-prostate-cancer/how-hormone-therapy-affects-you"}],"tags":[],"related":[],"cancers":["prostate"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Side effects"},"route":"/terms/gynaecomastia/","neighbours":{"cancer":[{"id":"prostate","kind":"cancer","name":"Prostate cancer","route":"/cancers/prostate/"}]}}