# Gynaecomastia

Source: https://onco.cc/terms/gynaecomastia/  
OnCo record `gynaecomastia` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: breast swelling in men; breast tenderness on hormone therapy

## Sources

- NICE NG131: prostate cancer, diagnosis and management: https://www.nice.org.uk/guidance/ng131/chapter/Recommendations
- Prostate Cancer UK: how hormone therapy affects you: https://prostatecanceruk.org/prostate-information-and-support/living-with-prostate-cancer/how-hormone-therapy-affects-you

## Connected records

- cancers: [Prostate cancer](https://onco.cc/cancers/prostate/)

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JSON: https://onco.cc/api/v1/entities/gynaecomastia.json