Histopathology image classification: Highlighting the gap between manual analysis and AI automation

The Independent Review of Gender Identity Services for Children and Young People (commonly, the Cass Review) was commissioned in 2020 by NHS England and NHS Improvement^[1] and led by Hilary Cass, a retired consultant paediatrician and the former president of the Royal College of Paediatrics and Child Health.^[2] It dealt with gender services for children and young people, including those with gender dysphoria and those identifying as transgender in England.

The final report was published on 10 April 2024,^[3] and it was endorsed by both the Conservative and Labour parties. The review led to a UK ban on prescribing puberty blockers to those under 18 experiencing gender dysphoria (with the exception of existing patients or those in a clinical trial).^[4] The Gender Identity Development Service (GIDS) at the Tavistock and Portman NHS Foundation Trust closed in March 2024 and was replaced in April with two new services, which are intended to be the first of eight regional centres.^[5] In August, the pathway by which patients are referred to gender clinics was revised and a review of adult services commissioned.^[6] In September, the Scottish government accepted the findings of a multidisciplinary team that NHS Scotland had set up to consider how the Cass Review's recommendations could best apply there.^[7] In England a delayed clinical trial into puberty blockers is planned for early 2025.^[8]

The review's recommendations have been widely welcomed by UK medical organisations.^{[9][10][11][12][13]} However, it has been criticised by a number of medical organisations and academic groups outside of the UK and internationally for its methodology and findings.^{[14][15][16][17][18][19]}

The Cass Review was commissioned by NHS England in September 2020, following a significant increase in referrals to the Gender Identity Development Service and a shift in the service from a psychosocial and psychotherapeutic model to one that included hormonal treatment.^[20][21] Hilary Cass, a former president of the Royal College of Paediatrics and Child Health, was asked by NHS England and NHS Improvement's Quality and Innovation Committee to chair an independent review with the aim of improving gender identity services for children and young people.^[20]

The Cass Review commissioned several peer-reviewed, independent systematic reviews into different areas of healthcare for children and young people with gender identity issues, including gender dysphoria.^[22][23] The reviews were carried out by academics at the University of York's Centre for Reviews and Dissemination, one of three bodies funded by the National Institute for Health and Care Research (NIHR) to provide a systematic review service to the NHS.^[24] The topics covered by the systematic reviews were:^[25]

• Characteristics of children and adolescents referred to specialist gender services^[26]
• Impact of social transition in relation to gender for children and adolescents^[27]
• Psychosocial support interventions for children and adolescents experiencing gender dysphoria or incongruence^[28]
• Interventions to suppress puberty in adolescents experiencing gender dysphoria or incongruence (puberty blockers)^[29]
• Masculinising and feminising hormone interventions for adolescents experiencing gender dysphoria or incongruence (cross-sex hormone therapy)^[30]
• Care pathways of children and adolescents referred to specialist gender services^[31]
• Clinical guidelines for children and adolescents experiencing gender dysphoria or incongruence^[32][33]

In the systematic reviews the report commissioned, tools such as the Mixed Methods Appraisal Tool and modified versions of the Newcastle–Ottawa scale were used to assess the quality of the studies available^[34][35] because no blinded controlled studies – those usually thought of as having the highest quality – were available.^[36] The systematic reviews performed meta-analyses to ascertain the best evidence-based knowledge on their respective subjects to inform the report's findings and recommendations.^[37][38]

In its collection of evidence, the report also carried out qualitative and quantitative research into young people with gender dysphoria and their health outcomes,^[39] carried out listening sessions and focus groups with service users and parents, held meetings with advocacy groups, and gathered existing documented insights into the lived experiences of patients.^[40]

The interim report^[41] of the Cass Review was published in March 2022. It said that the rise in referrals had led to the staff being overwhelmed, and recommended the creation of a network of regional hubs to provide care and support to young people. The report said that the clinical approach used by the Gender Identity Development Service (GIDS) "has not been subjected to some of the usual control measures"^[42] typically applied with new treatments, and raised concerns about the lack of data collection by GIDS.^[43][44] While GIDS initially followed the Dutch protocol, the interim review said there were "significant differences" in the current NHS approach.^[45] The report stated that children with comorbidities did not receive adequate psychological support, endocrinologists administering puberty blockers did not attend multidisciplinary meetings, and the frequency of those meetings did not increase when adolescents received puberty blockers, all of which the Dutch Approach recommends.^[45]

The interim report further said that GPs and other non-GIDS staff felt "under pressure to adopt an unquestioning affirmative approach"^[46] to children unsure of their gender, "overshadowing" other issues such as poor mental health. The Tavistock and Portman NHS Foundation Trust said "being respectful of someone's identity does not preclude exploration", and "We agree that support should be holistic, based on the best available evidence and that no assumptions should be made about the right outcome for any given young person."^[47]

The interim report said that there were "gaps in the evidence" over the use of puberty blockers. A public consultation was held and a further review of evidence by NICE said there was "not enough evidence to support the safety or clinical effectiveness of puberty suppressing hormones to make the treatment routinely available at this time." As a result, NHS England stopped prescribing them to children.^[48][49][50]

In April 2022, Health Secretary Sajid Javid told MPs that services in this area were too affirmative and narrow, and "bordering on ideological".^[51]

In November 2022, the World Professional Association for Transgender Health (WPATH), along with regional groups ASIAPATH, EPATH, PATHA, and USPATH, issued a statement criticising the NHS England interim service specifications based on the interim report. It contested several points in the report, including the pathologizing of gender diversity, the making of "outdated" assumptions regarding the nature of transgender individuals, "ignoring" newer evidence regarding such matters, and making calls for an "unconscionable degree of medical and state intrusion" into everyday matters such as pronouns and clothing choice, as well as into access to gender-affirming care. It further said that "the denial of gender-affirming treatment under the guise of 'exploratory therapy' is tantamount to 'conversion' or 'reparative' therapy under another name".^[14]

The final report of the Cass Review was published on 10 April 2024. It included several systematic reviews of scientific literature carried out by University of York, encompassing the patient cohort, service pathways, international guidelines, social transitioning, puberty blockers and hormone treatments.^[25]

The report states on page 20 that, "When the Review started, the evidence base, particularly in relation to the use of puberty blockers and masculinising or feminising hormones, had already been shown to be weak"; and that after the examination of over 100 pieces of potential evidence, that "there continues to be a lack of high-quality evidence in this area".^[52]

The report found no clear explanation for the rise in the number of children and adolescents with gender dysphoria, but said there was broad agreement for attribution to a mix of biological and psychosocial factors. The report's suggested influences included a lower threshold for medical treatment, social media-related mental health consequences, abuse, access to information regarding gender dysphoria, struggles with emerging sexual orientation, and early exposure to online pornography. The report considered a rise in acceptance of transgender identities to be insufficient to explain the increase.^{[53][26][54][55]}

A systematic review evaluated 11 studies assessing the outcomes of social transition in minors using a modified version of the Newcastle-Ottawa scale and considered nine to be low quality and two to be moderate quality.^[34][27] The report said that insufficient evidence was available to assess whether social transition in childhood has positive or negative effects on mental health, and that there was weak evidence for efficacy in adolescence. It also said that sex of rearing seems to influence gender identity, and hypothesised that early social transition may change the way a child's gender identity develops.^[56]

The report classified social transition as an "active intervention". It also advised caution in approaching social transition, and stressed the need for clinical involvement in determining risks and benefits, saying that it is not a role that can be undertaken without appropriate clinical training.^[55][57]

The report said that the evidence base and rationale for early puberty suppression remains unclear, with unknown effects on cognitive and psychosexual development. A systematic review^[29] examined 50 studies on the use of puberty blockers using a modified version of the Newcastle–Ottawa scale and considered only one to be of high quality, along with a further 25 being of moderate quality, and the remaining 24 being of low quality. The review concluded that the lack of evidence means no conclusions can be made regarding the impact on gender dysphoria and mental health, but did find evidence of bone health being compromised during treatment. The review disagreed with the idea of puberty blockers providing youth patients with "time to think", due to its finding that nearly all patients who went on blockers later decided to proceed on to hormone therapy.^{[58][29][59][55][60][61]} For youth assigned male at birth the report states that blockers taken too early can make a later penile inversion vaginoplasty more difficult due to insufficient penile growth.^[62] The report states one of the benefits of puberty blockers is the prevention of the irreversible changes of a lower voice and facial hair.^[63]

The report said that many unknowns remained for the use of hormone treatment among under-18s, despite longstanding use among transgender adults, with poor long-term follow-up data and outcome information on those starting younger. A systematic review^[30] evaluated 53 studies on transgender hormone therapy using a modified version of the Newcastle-Ottawa scale, and considered only one study to be of high quality, 33 moderate and 19 low quality. Overall, the review found some evidence that hormone treatment improves psychological outcomes after 12 months, but found insufficient and inconsistent evidence regarding physical risks and benefits. The review advised that there should be a 'clear clinical rationale' for the prescription of hormone therapy under 18 years of age.^{[58][30][59][57]}

A systematic review assessed ten studies on the efficacy of psychosocial support interventions in transgender minors using the Mixed Methods Appraisal Tool and considered only one to be of medium quality, with the remaining nine being of low quality. The review concluded that no robust conclusions can be made and more research is needed.^[28][64]

The report said that the evidence for psychosocial intervention as opposed to hormonal was "as weak as research on endocrine treatment", but that the result of psychological treatment was "either benefit or no change".^[65][66]

The report said that clinicians cannot be certain which children and young people will have an enduring trans identity in adulthood, and that for most, a medical pathway will not be the most appropriate. When a medical pathway is clinically indicated, wider mental health or psychosocial issues should also be addressed. Due to a lack of follow-up, the number of individuals who detransitioned after hormone treatment was unknown.^[58]

The Cass Review attempted to work with the Gender Identity Development Service and the NHS adult gender services to "fill some of the gaps in follow-up data for the approximately 9,000 young people who have been through GIDS to develop a stronger evidence base." However, despite encouragement from NHS England, "the necessary cooperation was not forthcoming."^[67][68]

A systematic review^[32][33] assessed 23 regional, national and international guidelines covering key areas of practice, such as care principles, assessment methods and medical interventions. Most guidelines were said to lack editorial independence and developmental rigour, and were nearly all influenced by the 2009 Endocrine Society guideline and the 2012 WPATH guideline, which were themselves closely linked. The Cass review questioned the guidelines' reliability, and concluded that no single international guideline regarding transgender care could be applied in its entirety to NHS England.^[58]

The report identified conflicting views among clinicians regarding appropriate treatment, with expectations of care sometimes deviating from clinical norms. It said that disputes over language such as "exploratory" and "affirmative" approaches meant it was difficult to establish neutral terminology. Some clinicians feared working with gender-questioning young people.^[69] The report said that some professionals were concerned about being accused of conversion practices, and were likewise concerned about legislation to ban conversion therapy. The report went on to say that many professionals were "overshadowed by an unhelpfully polarised debate around conversion practices".^[70][71]

The report made 32 recommendations covering areas including assessment of children and young people, diagnosis, psychological interventions, social transition, improving the evidence base underpinning medical and non-medical interventions, puberty blockers and hormone treatments, service improvements, education and training, clinical pathways, detransition and private provision.^[72]

Recommendations included:

• Care provision:
  • The use of standard psychological and pharmacological treatments for co-occurring and associated conditions like anxiety and depression.^[73]
  • Individualised care plans, including mental health assessments and screening for neurodivergent conditions such as autism.^[74]
  • That children and families considering social transition should be seen as soon as possible by a relevant clinical professional.^[75]
  • A designated medical practitioner who takes personal responsibility for the safety of children receiving care.^[23]
  • Longstanding gender dysphoria must be a mandatory prerequisite for medical transition, but is not the only criteria in deciding whether to allow a transition.^[76]
  • There should be a clear clinical rationale for the prescription of masculinising/feminising hormone therapy below the age of 18, and absolutely no masculinising/feminising hormone therapy below the age of 16.^[76]
  • Every case considered for medical transition must be discussed by a national multi-disciplinary team.^[76]
  • All minors should be offered fertility counseling and preservation prior to embarking upon a medical pathway.^[76]
  • A separate pathway should be established for the treatment of pre-pubertal treatment, who are ideally to be treated as early as possible.^[77]
• Changing how the NHS provides care:
  • The development of a regional network of centres, and continuity of care for 17–25 year olds.^[78][20]
  • The DHSC should direct NHS gender clinics to participate in the data linkage study, with the resulting research being overseen by NHS England's Research Oversight Board.^[79]
  • A multi-site service network should be developed as soon as possible, and the National Provider Collaborative to oversee the multi-disciplinary team should be established without delay.^[80]
  • To increase the available workforce, joint contracts should be used for health providers across a wide array of NHS services; and requirements for gender services should be built into the workforce planning for adolescent health services.^[81]
  • NHS England should develop a formal training program and competency framework for gender services, including a module on the holistic mental assessment framework.^[82]
  • Similar changes should be considered for adult gender services over the age of 25.^[83]
  • NHS England should ensure there are proper detransitioning services available, while also recognizing that detransitioners may not want to re-engage with services whose care they were previously under.^[84]
  • The DHSC and NHS England should consider the implications of private healthcare on any future requests by patients for treatment under the NHS.^[85]
  • The DHSC should work to define the dispensing responsibilities of pharmacists receiving private prescriptions, and work to halt the sourcing of transition medication obtained through prescriptions acquired in Europe.^[85]
• Future research:
  • The establishment of a full program of research which will carefully study the characteristics, interventions, and outcomes of every person seen by NHS gender services.^[76]
  • A central evidence and data resource for gender services should be established, with specifically defined datasets for both local and national services.^[82]
  • National infrastructure should be put in place to manage continual data collection on gender services, including through the ages of 17 to 25.^[82][83]
  • A unified research strategy shall be established to ensure the most meaningful data and numbers are collected.^[86]
  • A living systematic review over all of this research should be collected.^[77]
  • The NHS should establish requirements for the collection of data from patients of NHS gender services.^[87]

NHS England responded positively to the interim and final reports. As of April 2024 they have implemented a number of measures.^[5] In response to the interim report, in March 2024 NHS England announced that it would no longer prescribe puberty blockers to minors outside of use in clinical research trials, citing insufficient evidence of safety or clinical effectiveness.^[88][89] The Gender Identity Development Service (GIDS) at the Tavistock and Portman NHS Foundation Trust closed in March 2024.^[5] Two new services, located in the north west of England and in London, opened in April 2024, which are intended to be the first of up to eight regional services.^[5] These will follow a new service specification for the "assessment, diagnosis and treatment of children and young people presenting with gender incongruence".^[5] Puberty suppressing hormones are no longer routinely available in NHS youth gender services.^[5] New patients that have been assessed as possibly benefiting from them will be required to participate in a clinical trial that is being set up by the National Institute for Health and Care Research.^[22][90] A new board, chaired by Simon Wessely will encourage further research in the areas highlighted in the review as having a weak evidence base.^[5]

On August 7, 2024, NHS England announced a status update,^[91] including the publication of a new pathway specification^[91] for young people being considered for referral to specialist gender services. One recommendation is that those considering social transition be seen quickly by a clinical professional with relevant experience. The update also stated that "There is no defined clinical pathway in the NHS for individuals who are considering detransition. NHS England will establish a programme of work to explore the issues around a detransition pathway by October 2024".^[92]

The clinical trial to study the "potential benefits and harms of puberty suppressing hormones for children and young people" was due to start late 2024 but is now delayed to early 2025.^[8]

Conservative Prime Minister at the time Rishi Sunak said that the findings "shine a spotlight" on the need for a cautious approach to child and adolescent gender care.^[93][94] In their manifesto for the 2024 United Kingdom general election, the Conservatives promised to implement the Cass Review recommendations.^[95]

Wes Streeting, the Labour shadow Health Secretary at the time, welcomed the final report, saying that the report "must provide a watershed moment for the NHS's gender identity services" and committing the Labour Party to implementing the report's recommendations in full.^[96][97][98] Speaking to Sky News, Shadow Home Secretary Yvette Cooper said that Labour welcomed the Cass Review and committed to implementing all of its recommendations.^[99]

The Green Party of England and Wales described the Review as "an important part of the process of improving healthcare for children and young people" while noting "some concerns have been raised about the review, particularly in relation to accessing NHS care following private healthcare, concerns around data inclusion/exclusion and a question around a conflict of interest of one of the researchers."^[100]

The British Equality and Human Rights Commission, a non-departmental public body, issued a statement in April 2024 and described it as a "vital milestone" and called for all service providers to fully implement the recommendations of the review.^[101]

The Scottish Government said it would "take the time to consider the findings".^[102] Humza Yousaf, First Minister of Scotland and SNP leader at the time of the final report's release, said that while the Scottish government would discuss the Cass Review with health authorities, it would leave its implementation up to clinicians.^[103]

The Welsh Senedd initially voted against a motion tabled by the Welsh Conservatives Shadow Social Justice Minister to accept the findings of the Cass Review in full. Subsequently, the Senedd voted unanimously to pass an amended motion noting "NHS England has concluded there is not enough evidence to support the safety or clinical effectiveness of puberty suppressing hormones for the treatment of gender dysphoria in children and young people" and "the Welsh Government will continue to develop the transgender guidance for schools taking account of the Cass review and stakeholder views".^[104]

Citing the Cass Review findings, in August 2024 the Northern Ireland Executive agreed to the extension of the ban on the private sale and supply of puberty blockers to Northern Ireland.^[105] This was supported by all parties in the Executive at the time apart from the Alliance Party.^[106]

The British Psychological Society said in April 2024 that they support "the report's primary focus of expanding service capacity across the country" and acknowledged that "while psychological therapies will continue to have an incredibly important role to play in the new services, more needs to be done to assess the effectiveness of these psychological interventions." BPS president Roman Raczka commended the review as "thorough and sensitive", in light of the complex and controversial nature of the subject. He said "it will take time to carefully review and respond to the whole report" but he was sure the field of psychology would learn lessons from it. He welcomed the recommendation for a consortium of relevant bodies to develop better trainings and upskill the workforce.^[9]

The Royal College of Psychiatrists welcomed the report and strongly agreed with some of its recommendations. They supported the emphasis on a holistic and person-centred approach and research to improve the evidence basis for treatment protocols. They said that some of its trans members, and the wider trans community, had concerns about availability of treatments while awaiting research, said there was "a strong view that the report makes assumptions in areas such as social transition and possible explanations for the increase in the numbers of people who have a trans or gender diverse identity, which contrasts with the more decisive statements about treatment approaches", and called for direct and comprehensive involvement of those with lived experience.^[10]

The Royal College of Paediatrics and Child Health (RCPCH) said they would take the time to review the recommendations in full and said that data collected had identified a lack of confidence by paediatricians and GPs to support this patient group, which the RCPCH pledged to address by developing new training. RCPCH President's Steve Turner thanked Cass and her team for the "massive undertaking" and said they would consider the report's recommendations.^[11] In August 2024, the RCPCH acknowledged there had been some academic criticism of the Cass Review and a call to pause the implementation of recommendations. They regarded this as a "backwards step", further delaying care that already has "unacceptable waiting times". While remaining mindful of "emerging criticisms of any chosen approach", their priority is "that this group of children receive timely, holistic and high-quality care".^[107]

In response to the Cass Review, the Royal College of General Practitioners in July 2024 updated its position statement on the role of the GP in transgender care. They advise that, for patients under 18, no GP should prescribe puberty blockers outside of a clinical trial, and the prescription of gender-affirming hormones should be left to specialists. The GCGP affirms it will fully implement the recommendations of the Cass Review. They specifically highlight recommendations for services 17–25 year olds, noting that some other fields are moving to a 0–25 service for better continuity of care, and the need for additional services for those people considering detransition.^[12]

The Academy of Medical Royal Colleges (AoMRC) released a statement in August 2024 in support of the report's recommendations, stating that "further speculative work risks greater polarisation", and that "our focus should be on implementing the recommendations of the Cass Review".^[13]

The British Medical Association (BMA) initially called for a pause on the review's implementation while it conducted an evaluation, due to be completed by January 2025.^[19] The call prompted opposition from some doctors, more than 1,500 of whom signed an open letter to the BMA characterising their planned evaluation as a "pointless exercise".^[108][109] In September 2024, the BMA council voted to instead maintain a neutral position on the issue until the completion of its own evaluation.^[110][111]

The UK's Association of LGBTQ+ Doctors and Dentists (GLADD) issued a response to the Cass Review in November 2024. Of the 32 recommendations of the Cass Review, GLADD supported 15, said that it could support a further 14 but with provisos, could not support two, and was neutral on one.^[112] It did not criticise or appraise the methodology of the Review, saying, "We do not feel that as a committee we have sufficient expertise to do justice to such evaluation."

The American Academy of Pediatrics and the Endocrine Society both responded to the report by reaffirming their support for gender-affirming care for minors and saying that their current policies supporting such treatments are "grounded in evidence and science".^[113]

The Canadian Pediatric Society responded to the report by saying "Current evidence shows puberty blockers to be safe when used appropriately, and they remain an option to be considered within a wider view of the patient's mental and psychosocial health."^[114]

The Amsterdam University Medical Center put out a statement saying that while it agrees with the goals of reducing wait times and improving research, it disagrees that the research-base for puberty blockers is insufficient, asserting that puberty blockers have been used in trans care for decades.^[115]

The Royal Australian and New Zealand College of Psychiatrists rejected calls for an inquiry into trans healthcare following the release of the Cass Review.^[116] They characterised the Cass Review as one review among several in the field.^[116] They emphasised that, "assessment and treatment should be patient centred, evidence-informed and responsive to and supportive of the child or young person's needs and that psychiatrists have a responsibility to counter stigma and discrimination directed towards trans and gender diverse people."^[116]

The Japanese Society of Psychiatry and Neurology published updated guidelines in August 2024 on the treatment of gender dysphoria. The guidelines considered the Cass Review, describing it as specific to the unique situation in the UK, noted criticism of the Cass Review by other international organizations, and stated that the WPATH SOC8 considered more systematic reviews. The guidelines further noted it is "self-evident" that, unless puberty is suppressed, development of sex characteristics are irreversible in AMAB individuals. The society stated they would continue to track and recommend prescriptions of puberty blockers in Japan to minors and expand to tracking discontinuations and switches to hormone therapy.^[117][118]

The World Professional Association for Transgender Health (WPATH) released an email statement saying that the report "is rooted in the false premise that non-medical alternatives to care will result in less adolescent distress" and further criticised recommendations which "severely restrict access to physical healthcare, and focus almost exclusively on mental healthcare for a population which the World Health Organization does not regard as inherently mentally ill".^[119][120] An official statement expanded on these concerns, saying Hilary Cass had "negligible prior knowledge or clinical experience", asserting that "the (research and consensus-based) evidence is such to recommend that providing medical treatment including puberty-blocking medication and hormone therapy is helpful and often life-saving", and questioning the provision of puberty blockers only in the context of a research protocol: "The use of a randomized blinded control group, which would lead to the highest quality of evidence, is ethically not feasible."^[121]

The Professional Association for Transgender Health Aotearoa (PATHA), a New Zealand professional organisation, said that the Cass Review made "harmful recommendations" and was not in line with international consensus, and that "Restricting access to social transition is restricting gender expression, a natural part of human diversity." They further said that several people involved in the review "previously advocated for bans on gender-affirming care in the United States, and have promoted non-affirming 'gender exploratory therapy', which is considered a conversion practice."^[16][122]

A joint statement by Equality Australia signed by the Australian Professional Association for Trans Health (AusPATH) and PATHA among others said the review "downplays the risk of denying treatment to young people with gender dysphoria and limits their options by placing restrictions on their access to care".^{[16][123][124]}

The report was praised by some academics in the UK, who agreed with its findings stating a lack of evidence;^{[97][67][125]} while others both in the UK^[126] and internationally^{[114][127][128]} disagreed with the report's methodology and findings.

The Integrity Project at Yale Law School released a white paper in July 2024, critiquing the Cass Review, accusing it of having "serious flaws."^{[129][130][131]} The white paper, co-authored by a group of eight legal scholars and medical researchers, argues that the Cass Review "levies unsupported assertions about gender identity, gender dysphoria, standard practices, and safety of gender-affirming medical treatments, and it repeats claims that have been disproved by sound evidence" and that "is not an authoritative guideline or standard of care, nor is it an accurate restatement of the available medical evidence on the treatment of gender dysphoria."^[129][130]

In September 2024, the Journal of Adolescent Health, the official publication for the international Society for Adolescent Health and Medicine published a paper titled "Gender Affirming Care Is Evidence Based for Transgender and Gender-Diverse Youth" noted other scholars' "lengthy and nuanced rebuttals to the Cass report", and states "Cass' conclusions generally focus on limiting or minimizing medical gender-affirming care (GAC) for youth and she also minimizes the robust data and the potential negative impact of increasing barriers for an already disenfranchised group." The paper outlines that "GAC for youth is well supported by evidence and critiques of the available literature and the needs for continued research do not warrant removal of access to this important care." and highlighted that some of the criticism that claim lack of evidence are asking for randomized controlled trials (RCT) which would not be ethically feasible for youth experiencing gender dysphoria.^[132]

Amnesty International criticised "sensationalised coverage" of the review, stating "This review is being weaponised by people who revel in spreading disinformation and myths about healthcare for trans young people."^[18][133] Trans youth charity Mermaids and the LGBTQIA+ charity Stonewall endorsed some of the report's recommendations, such as expanding service provisions with the new regional hubs, but raised concerns the review's recommendations may lead to barriers for transgender youth in accessing care.^[122]

Gender-critical organisations including Sex Matters and Genspect welcomed the report. Stella O'Malley of Genspect expressed concern that if a conversion therapy ban were to criminalise any exploration into why a child identifies as trans, it "would ban the very therapy that Cass is saying should be prioritised".^[134][135]

In the week after the release of the final report, Cass described receiving abusive emails and was given security advice to avoid public transport.^[136] She also said that "disinformation" had frequently been spread online about the report. Cass said "if you deliberately try to undermine a report that has looked at the evidence of children's healthcare, then that's unforgivable. You are putting children at risk by doing that."^[136] There were widespread misleading claims from critics of the report that it had dismissed 98% of the studies it collected and all studies which were not double-blind experiments.^[137] Cass described these claims as being "completely incorrect". Although only 2% of the papers collected were considered to be of high quality, 60% of the papers, including those considered to be of moderate quality, were considered in the report's evidence synthesis.^{[38][138][139]} Cass criticised Labour MP Dawn Butler for repeating, during a debate in the House of Commons, inaccurate claims that the review had dismissed more than 100 studies.^{[140][141][142]} After talking with Cass, Butler used a point of order to admit her mistake and correct the record in Parliament, stating the figure came from a briefing she had received from Stonewall.^{[139][143][144][145]}

In an interview with The New York Times in May 2024, Hilary Cass expressed concern that her review was being weaponized to suggest that trans people do not exist, saying "that's really disappointing to me that that happens, because that's absolutely not what we're saying". She also said that the review was not about defining what trans means or rolling back health care, stating: "There are young people who absolutely benefit from a medical pathway, and we need to make sure that those young people have access — under a research protocol, because we need to improve the research — but not assume that that's the right pathway for everyone."^[146]

In an interview with WBUR-FM in May 2024, Cass responded to WPATH's criticism about prioritising non-medical care, saying the review did not take a position about which is best. Cass hoped that "every young person who walks through the door should be included in some kind of proper research protocol" and for those "where there is a clear, clinical view" that the medical pathway is best will still receive that, and be followed up to eliminate the "black hole of not knowing what's best". Responding to claims that the review assumed a trans outcome was the worst outcome for a child, Cass emphasised that a medical pathway, with lifetime implications and treatment, required caution but "it's really important to say that a cis outcome and a trans outcome have equal value".^[147]

In May 2024, then Health Secretary Victoria Atkins implemented an emergency three-month ban on the prescription of puberty blockers by medical providers outside of the NHS. It went into effect on 3 June 2024 and was set to expire on 3 September 2024. The ban restricted their use to only those already taking them, or within a clinical trial. In July, this ban was challenged by campaign groups TransActual and Good Law Project who brought a legal case arguing the ban was unlawful.^[148] On 29 July 2024 the High Court of Justice ruled that the ban was lawful.^{[149][4][150]}

The Health Secretary, Wes Streeting welcomed the decision which he characterized as “evidence led”, and said efforts were being made to set up a clinical trial to "establish the evidence on puberty blockers".^[4][150] Following the ruling, TransActual announced that they would not appeal the decision due to limited funds and the unlikelihood of an appeal being heard before the ban expires.^[151]

On 22 August 2024, the government extended the emergency ban an additional three months and is now set to expire on 26 November 2024. The ban was also extended to cover Northern Ireland, following agreement from the Northern Ireland Executive and came into effect on 27 August 2024.^{[152][153][154]} On 6 November 2024 the ban was extended again to 31 December 2024.^[155] On 11 December 2024, the ban was renewed indefinitely and is set to be reconsidered in 2027.^[156][157]

The Cass Review did not cover adult care, and in April 2024, NHS England said it would also initiate a review of all its adult gender clinics in response.^[158] NHS England National Director of Specialised Commissioning John Stewart sent a letter to Cass stating that it would review the use of gender-affirming transgender hormone therapy in adults in a similar manner as was done for puberty blockers in the Cass Review.^{[159][160][161]}

In May 2024, Cass wrote to NHS England, to pass on the feedback regarding adult care from clinicians who had approached her during the Review process. Clinicians across the country in adult gender services had expressed concern about both the clinical practice and model of care. Some clinicians in other settings, especially general practice, had raised concerns about the treatment of patients under their care.^[162] On 7 August, NHS England included a response to the adult care letter, in a status report for the under-18s services.^[163]

On 8 August, they stated that the review of adult services would be led by Dr. David Levy, medical director for Lancashire and South Cumbria integrated care board, to assess "the quality (i.e. effectiveness, safety, and patient experience) and stability of each service, but also whether the existing service model is still appropriate for the patients it is caring for"; and that Dr. Levy would work with a group of "expert clinicians, patients and other key stakeholders, including representatives from the CQC, Royal Colleges and other professional bodies and will carefully consider experiences, feedback and outcomes from clinicians and patients, past and present". The first onsite visits are planned to start in September 2024. The findings will be used to support an updated adult gender service specification which will then be liable to engagement and public consultation. Unlike the Cass Review, the review of adult gender services is expected to be completed within months, rather than years.^{[6][164][165]}

In December 2024, it was reported that a number of GPs had begun refusing or withdrawing hormone treatment from adult trans patients, for reasons including both the Cass Review itself, and the Royal College of GP's response to the Cass Review – despite the Cass Review only applying to youth services.^[166]

On 18 April 2024, NHS Scotland announced that it had paused prescribing puberty blockers to children referred by its specialist gender clinic.^[167] The chief medical officer of Scotland set up a multidisciplinary clinical team to assess how the Cass Review's 32 recommendations might be applied to NHS Scotland. Their Cass Review – implications for Scotland: findings report was published in July 2024 and found that the majority of recommendations were applicable to NHS Scotland to a varying degree, with some modification dealing with differences in the Scottish health service. They recommended that the use of puberty blockers be paused until clinical trials are begun. NHS Scotland will participate in the forthcoming UK study.^[168] That report was fully accepted by the Scottish government in September. Among the changes recommended are that the gender identity service for children and young people should be moved to a paediatric setting and more than one service offered across the regions. In common with other specialities, a referral to these services will now be required to have come from a clinician rather than the patient themselves.^[7]

In October 2024, the Charity Commission for England and Wales released an inquiry into the trans children's charity Mermaids. The inquiry issued "regulatory advice and guidance" to the charity telling them to further consider the Cass Review's findings and conclusions as well as review the guidance and positions on their website regarding puberty blockers.^[169]

• 21st-century anti-trans movement in the United Kingdom
• Bell v Tavistock
• Evidence-based medicine
• Time to Think
• Transgender health care
• Transgender rights in the United Kingdom
• LGBTQ rights in the United Kingdom
• Transgender history in the United Kingdom

• Official website