In the years leading up to the Cass Review, several GIDS staff members voiced concerns over the evidence base for the treatments being given and the extent of prior assessment.
It said the rise in referrals had led to staff being overwhelmed, and recommended the creation of a network of regional hubs to provide care and support to young people.
The report also said that diagnosis of gender-related distress sometimes led to "diagnostic overshadowing", where comorbidities such as poor mental health – which were usually managed by local services – were overlooked.
[85] In response, the Tavistock and Portman NHS Foundation Trust said "being respectful of someone's identity does not preclude exploration", and that it agreed "support should be holistic, based on the best available evidence" without making assumptions about "the right outcome for any given young person".
[66][91] The report states that the existing evidence for both endocrine (puberty blockers and hormone therapy) and non-endocrine treatments (psychosocial interventions) in children and adolescents with gender incongruence is weak.
[i] 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.
[103] The report said 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.
[18] On August 7, 2024, NHS England announced a status update, for young people being considered for referral to specialist gender services, including the publication of a new pathway specification.
[21] 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.
[142] Wes Streeting, the Labour shadow Health Secretary at the time, welcomed the final report, saying it was "a watershed moment for the NHS's gender identity services".
[143][144][145][146] In its statement, LGBT+ Labour urged their party to "exercise caution in responding to the review", saying that while it got things right, it had "received credible criticism from trans advocacy groups and researchers".
[148] The Equality and Human Rights Commission, a non-departmental public body, described the Cass Review as a "vital milestone" and called for all service providers to fully implement its recommendations.
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".
They stated they were engaged with NHS England and as a part of this would "encourage NHSE to consider emerging criticisms of any chosen approach, as would be the case in the delivery of any other children's health service.
[167] In July 2024, the UK's Association of LGBTQ+ Doctors and Dentists (GLADD) criticised the British Medical Journal's coverage of the Cass Review, stating that some recommendations could be beneficial while others could create new barriers to care for transgender youth.
[168] In October, GLADD released an official response to the review, stating they were broadly supportive of its recommendations but were "concerned with what we believe to be an ingrained bias against the autonomy of trans people throughout the narrative text" which had also been noted by others.
[171] The Canadian Pediatric Society responded that "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.
[175][176] The World Professional Association for Transgender Health (WPATH) released an email statement saying 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".
[177][178] An official statement expanded on these concerns, saying Hilary Cass had "negligible prior knowledge or clinical experience" and that "the (research and consensus-based) evidence" suggests medical treatments such as puberty blockers and hormone therapy were "helpful and often life-saving".
It questioned 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.
[11][180] 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".
[180] In June 2024, the University and College Union's (UCU) national executive committee unanimously passed a motion criticising the review's methodology, sourcing and claims.
Concerns included Cass's selection without consideration of other candidates, "secrecy" regarding the report's commissioning, and "explicit exclusion of any trans people from involvement in the Governance Assurance Group, on the basis of potential bias".
[67][204][205] Cass criticised Labour MP Dawn Butler for repeating inaccurate claims that the review had dismissed more than 100 studies during a debate in the House of Commons.
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".
Further, the paper criticises the Cass Review for suggesting that "peer and socio-cultural influence" are driving the increase in referrals, a claim which originates from a single article that has been heavily corrected for numerous well-documented fatal flaws.
[199] PATHA criticized the inclusion of "a number of people" in the review and advisory group who had "previously advocated for bans on gender affirming care in the United States".
[227][228] The Association of LGBTQ+ Doctors and Dentists (GLADD) said the Cass Review "may implicitly pathologise trans and non-binary identities" or "perpetuate stigmatisation of this population", including in its discussions of social transition, the suggestion that gendered toy preference is biologically deterministic, and the language used regarding masculinising/feminising hormones as a negative or undesirable outcome.
In reference to one question, where a third of respondents agreed with the statement "There is no such thing as a trans child", the authors write: "Denying the existence of transgender people of any age is an invalid professional viewpoint.