Summary

This review gathered 39 studies on breast removal surgery for young people with gender distress and rated how trustworthy the evidence was. Nearly all only followed operated patients, with no comparison group. Only short-term surgical complications were rated high-quality evidence, and they were uncommon: no deaths, about 2% to 3% loss of the nipple or skin graft through tissue death, and about 5% thick scarring. For the results that matter most, such as gender distress, mental health, suicide attempts, quality of life and regret, the evidence was weak or very weak. One study did suggest people were about half as likely to self-harm after surgery. The authors call for better studies. The review shows the evidence is weak; it does not show that surgery fails to help. It was funded by SEGM, a group that urges caution, and surgeons have challenged its framing in published letters.

Key findings

• 回顧找到 39 項研究，檢索到 2023 年 6 月：只有 3 項比較了不同組別，2 項在手術前後測量人們；其他 34 項只描述了接受手術的患者。
• 高品質證據只來自手術併發症的研究：沒有死亡（5 項研究），每 1,000 人中約 20 人因組織壞死失去乳頭或皮膚移植（13 項研究），每 1,000 人中約 10 人失去皮瓣（3 項研究），每 1,000 人中約 50 人出現厚疤痕（12 項研究）。
• 兩項比較手術與束胸的研究，對於與胸部相關的性別困擾以及對身體和胸部的滿意度，提供了非常薄弱的證據。
• 一項比較手術與未手術的研究，對於痛苦和自殺未遂提供了非常薄弱的證據，並對於手術後自傷（沒有自殺意圖）的可能性約降低一半提供了薄弱的證據。
• 生活品質、憂鬱、自殺死亡、對胸部的滿意度和後悔，全都被評為非常薄弱的證據，主要是因為沒有對照組。
• 原本計畫檢查結果是否因其他心理健康狀況、困擾開始的年齡或性傾向而不同，但無法進行，而自殺想法、性功能和後續手術也沒有被評估。
• 作者呼籲進行及時往前追蹤患者的研究，並在合乎倫理的情況下進行隨機試驗，以提供給患者、外科醫師、指引撰寫者和政策制定者參考。

Abstract

BACKGROUND: Gender dysphoria (GD) refers to psychological distress associated with the incongruence between one's sex and one's gender. In response to GD, birth-registered female patients may choose to undergo mastectomy. In this systematic review, the authors summarize and assess the certainty of the evidence about the effects of mastectomy. METHODS: We searched MEDLINE, Embase, PsycINFO, Social Sciences Abstracts, LGBTQ+ Source, and Sociological Abstracts through June 20, 2023. We included studies comparing mastectomy to no mastectomy in birth-registered patients younger than 26 years with GD. Outcomes of interest included psychological and psychiatric outcomes, and physical complications. Pairs of reviewers independently screened articles, abstracted data, and assessed risk of bias of the included studies. We performed meta-analysis and assessed the certainty of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. RESULTS: We included 39 studies. Observational studies (n = 2) comparing mastectomy to chest binding provided very low-certainty evidence for the outcome of GD. One observational study comparing mastectomy to no mastectomy provided very low-certainty evidence for the outcomes of global functioning and suicide attempts, and low-certainty evidence for the outcome nonsuicidal self-injury (adjusted OR, 0.47; 95% CI, 0.22 to 0.97). Before-and-after (n = 2) studies provided very low-certainty evidence for all outcomes. Evidence from case series (n = 34) studies ranged from high to very low certainty. CONCLUSIONS: Case series studies demonstrated high-certainty evidence for the outcomes of death, necrosis, and excessive scarring; however, these are limited in methodologic quality. In comparative and before-and-after studies, the evidence ranged from low to very low certainty.

Conclusion

The best available evidence reporting the effects of mastectomy in individuals with GD ranged from high to very low certainty. High certainty evidence in this SR was derived from case series studies only. High-certainty evidence from prospective cohort studies and, if ethical, randomized controlled trials, are needed to describe the short- and long-term effects of mastectomy in individuals with GD on mental health outcomes. Higher certainty evidence would be useful to individuals with GD considering chest masculinization; clinicians and surgeons involved in their care; guideline developers; and policy makers and stakeholders who make decisions about treatment related to GD.