Cass report urges ‘extreme caution’ in prescribing puberty blockers to trans youth

The Cass report, an independent review into the provision of healthcare for trans youth in England, has urged clinicians to use “extreme caution” when prescribing puberty blockers to trans youth.

A full 400-page report into England’s model of care for trans under-18s published on Wednesday (10 April) claimed that there is “weak evidence” suggesting that puberty-blocking hormones positively or negatively impact gender dysphoria, while deeming historical studies into its effects to be of “poor quality.”

Puberty-blocking hormones refer to medication that suppresses unwanted puberty-related changes. They have been labelled as physically reversible by NHS England in the past.

NHS England commissioned an independent review headed by Dr Hilary Cass in 2020 to address the rise in referrals to the country’s only youth gender clinic.

The report published this week expands the recommendations made in an interim report released in March 2022, which called for a decentralised approach to care provision in England in the form of regional hubs.

It found that there is “no simple explanation” for the increase in young people who identify as transgender, non-binary, or gender nonconforming and that there are “conflicting views” in how to provide care for trans youth.

A person in a tank top stands outside infront of the Tavistock Centre sign.
The Tavistock Centre was previously the location of the only youth gender clinic in England. (Getty)

Cass also noted that a “considerable amount of research” had been published around clinical decision-making for youth gender services but that evidence suggest that the work is of “poor quality” and unreliable.

One example it points to is the World Professional Association of Transgender Healthcare (WPATH), an internationally recognised body for trans healthcare guidance, which it said lacks “developmental rigour.”

The report also found that clinical guidelines in other countries did not apply to England “in its entirety.”

In a statement, Cass said: “What I am recommending is an expansion of capacity distributed across the country, grounded in paediatric services and delivered in a consistent way.

“A much more holistic offer of care that considers the child as a whole person and not just through the lens of their gender identity,” she continued. “And the development of a robust research environment to provide evidence on long-term outcomes and efficacy of different interventions so that future care is informed by robust evidence.”

Cass report recommends ‘separate pathways’ for pre-pubertal children and families

As well as decentralising the model of care to regional hubs across England, the Cass report also recommends that young people referred to a youth gender clinic be assessed to “inform an individualised care plan” including screenings for “neurodevelopmental conditions” such as autism, depression, anxiety, and others.

Services are also recommended to establish separate pathways for pre-pubertal children and their families and prioritise them among referrals.

Other pathways include a “follow-through” service for 17-25 year olds that would transition patients to adult gender clinics.

While puberty blockers for patients aged 16 and up will remain available only for clinic trials by NHS England, the report recommended clinical providers exercise “extreme caution,” adding that there should be a “clear clinical rationale” for providing puberty-blocking hormones to under-18s.

Puberty blockers have been inaccessible outside of clinic trials for some time, with further steps to prevent prescriptions in March 2024.

“I have had to make recommendations based on the currently available information,” Cass wrote. “I am very aware that this is a point in time and as new evidence is gathered, different insights might emerge.”

The review also claimed that, while research suggests that hormone treatment “reduces” the elevated risk of suicide, there is “no clear evidence” that social transition has any positive or negative mental health outcomes.

“However, those who had socially transitioned at an earlier age and/or prior to being seen in clinic were more likely to proceed to a medical pathway.”

‘I’ve no doubt that much of what’s been written in these reports won’t be fully implemented’

Despite agreeing with a number of the recommendations made in the Cass report, clinical psychologist and director of the independent gender service, Gender Plus, Dr Aiden Kelly, said that he disagrees with the report’s emphasis on the needs of detransitioners.

“It’s not to deny that those needs are important, of course, we don’t want to make anyone’s life harder or more complicated than it needs to be, but to focus on those needs of the very small few at the expense of the large majority doesn’t make sense to me.”

Kelly said that while the findings of the report were not wholly surprising, the model of care is pointing generally in the right direction.

“Being someone who has worked in this area for quite a long time … I’ve always been aware of that kind of holistic, comprehensive service that can meet their needs not just in gender, but other aspects of young people’s needs.

“That was the case in 2020 and remains the case. The bit that’s different now versus 2020, sadly, [is that] we’re in a far worse position than we were when the review was commissioned.”

A close up of a trans activist with the words "protect trans kids" written on their face.
A close up of a trans activist with the words “protect trans kids” written on their face. (Getty)

What Kelly is most fearful of, however, is the level to which the review’s recommendations will be fully implemented, saying that it’s “hard to remain hopeful” of a significant change.

New regional hubs which opened for preliminary care in April were described as “nowhere near ready” by sources earlier this month.

“I’ve no doubt that much of what’s been written in these reports won’t be able to be fully implemented,” Kelly said. “These were already seen with these early regional hubs. They don’t know how to fill these positions.

“It’s been a bit of an example of perhaps how not to provide a pathway. They’ve shut down [The Tavistock Service] without being able to know how to fully resource the new replacement services.”

Stonewall’s director of campaigns and human rights, Robbie de Santos, shared similar qualms in a statement to PinkNews, saying that “what is important, above all, is that trans and gender-diverse children get the quality healthcare they need and deserve.”

“Many recommendations could make a positive impact – such an expanding provision of healthcare by moving away from a single national service towards a series of regional centres, while recognising that there are many different treatment pathways that trans young people might take.”

Who is Dr Hilary Cass?

Dr Hilary Cass: a middle-aged woman with glasses and short red hair and a purple top
Dr Hilary Cass (

Dr Hilary Dawn Cass is a former consultant in paediatric disability at St Thomas’ Hospital, London, who was awarded an OBE for her work in child healthcare in 2015. She was also the President of the Royal College of Paediatrics and Child Health from 2012 to 2015.

From 1994 to 2009 Dr HIlary Cass was a consultant in paediatric disability at Great Ormond Street Hospital (GOSH). In 2013 it was revealed she left Great Ormond Street Hospital after raising concerns about patient safety. She emailed chief executive Dr Jane Collins a detailed account of her concerns about poor staffing, low morale and bad communication between departments, and was subsequently demoted.

She took them to court for constructive dismissal and the hospital agreed on a settlement.

On 10 March 2022, Cass released an interim report from the Cass Review calling for regional centres to care for trans youth “as soon as feasibly possible”, suggesting that local centres become “direct service providers, assessing and treating children and young people who may need specialist care, as part of a wider pathway”.