Summary

The Cass Review was set up after referrals to England's child gender service rose sharply and the patients changed to mostly teenage girls, many with autism or mental health problems. Its final report found that care had rested on 'remarkably weak' evidence. Reviews by the University of York could draw no conclusions on how puberty blockers (drugs that pause puberty) affect gender distress or mental health, and found only limited evidence for hormones. Cass recommended whole-person assessment, standard psychological support, blockers only in a research trial, 'extreme caution' with hormones before 18, national review of every medical case, and regional services. It is the most thorough review of its kind, and later reviews agree the evidence is weak. Its methods are disputed, critics and defenders both have stakes, and some advice rests on judgement rather than data.

Key findings

• 2020年にNHS Englandが設置し、2024年4月10日に公表された388ページの最終報告書は、イングランドの子どもと若者のジェンダーサービスに関する32の提言を行っています。
• 思春期ブロッカーに関するヨーク大学のレビューは50件の研究を調べました（高品質1件、中程度25件、低品質24件）。性別への苦痛、メンタルヘルス、脳の発達への影響については結論を出せず、骨の健康や身長に害がある可能性があるとしました。
• 異性ホルモンに関するヨークのレビューは53件の研究を調べました（高品質1件、中程度33件、低品質19件）。治療中にメンタルヘルスが改善する可能性があるという中程度の質のエビデンスは見つかりましたが、他の影響については結論を出せませんでした。
• レビューは、自閉症および類似の状態の確認やメンタルヘルスの評価を含む全人的な評価と、苦痛やその他の状態に対する標準的で実証された心理療法と薬物療法を提言しています。
• 思春期ブロッカーは研究の中でのみ提供されるべきとされました（NHS Englandは臨床試験を進めました）。16歳からのホルモンには「細心の注意」と、18歳まで待たない明確な理由が必要で、医学的治療のすべての症例は国の専門家パネルに回されるべきとされました。
• レビューは、WPATH（世界トランスジェンダーヘルス専門家協会）のものを含むガイドラインは、慎重に作成されていなかったと指摘しました。NHSの成人ジェンダークリニック7か所のうち6か所が、長期的な結果の研究へのデータ提供を拒否しており、レビューは参加を指示すべきだとしています。
• 幼い子どもの社会的トランジション（新しい名前、服装、代名詞）を決める家族は、早い段階で経験のある臨床医に会うべきであり、すべての若者は、医学的治療の前に妊孕性に関する助言と卵子や精子の保存を提供されるべきとされました。
• この報告書は、Yale大学のIntegrity Project（McNamaraら、2024）と査読付き論文（Nooneら、2025）で批判されました。Archives of Disease in Childhood（Cheungら、2025）とJournal of Sex & Marital Therapy（McDeavittら、2025）では擁護されました。

Abstract

1. The aim of this Review is to make recommendations that ensure that children and young people who are questioning their gender identity or experiencing gender dysphoria receive a high standard of care. Care that meets their needs, is safe, holistic and effective. At its heart are vulnerable children and young people and an NHS service unable to cope with the demand. 2. Yet from the start, the Review stepped into an arena where there were strong and widely divergent opinions unsupported by adequate evidence. The surrounding noise and increasingly toxic, ideological and polarised public debate has made the work of the Review significantly harder and does nothing to serve the children and young people who may already be subject to significant minority stress. 3. Within this context the Review set out to understand the reasons for the growth in referrals and the changing epidemiology, and to identify the clinical approach and service model that would best serve this population. 4. There are conflicting views about the clinical approach, with expectation at times being far from usual clinical practice. This has made some clinicians fearful of working with gender-questioning young people, despite their presentation being similar to many children and young people presenting to other NHS services. 5. Although some think the clinical approach should be based on a social justice model, the NHS works in an evidence-based way. Whilst navigating a way through the surrounding ‘culture war’, the Review has been acutely and increasingly aware of the need for evidence to support its thinking and ultimately the final recommendations made in this report. 6. When the Review started, the evidence base, particularly in relation to the use of puberty blockers and masculinising/feminising hormones, had already been shown to be weak. There was, and remains, a lot of misinformation easily accessible online, with opposing sides of the debate pointing to research to justify a position, regardless of the quality of the studies.

Conclusion

The Cass Review concludes that children and young people questioning their gender identity or experiencing gender dysphoria require a high standard of care that is safe, holistic, and evidence-based. The Review found that the evidence base for medical interventions, particularly puberty blockers and masculinising/feminising hormones, is weak, and that clinical practice has been complicated by a toxic, polarised public debate. The ten key recommendations focus on: (1) ensuring services meet standard NHS care standards with clear clinical leadership; (2) implementing holistic assessment frameworks including screening for neurodevelopmental conditions and mental health; (3) using standard evidence-based psychological and psychopharmacological treatments; (4) ensuring early clinical involvement in decisions about social transition of pre-pubertal children; (5-6) establishing robust research and data collection programmes to improve the evidence base; (7) requiring long-standing gender incongruence as essential but not sufficient for medical treatment; (8) exercising extreme caution in prescribing hormones from age 16; (9) requiring national Multi Disciplinary Team review for all medical treatment cases; and (10) offering fertility counselling and preservation before any medical pathway. The Review emphasises that the NHS must work in an evidence-based way rather than following a social justice model, and that the needs of vulnerable children and young people must be prioritised over ideological positions.