Tell me if you’ve heard of this before: a government responds to the noise around gender-affirming care by setting up an independent review board. This board is tasked with reviewing the evidence, and coming up with guidelines that will inform government policy about the process.
It sure sounds an awful lot like the Cass Review, doesn’t it? The report which has been repeatedly used to deny health care to transgender people, despite withering critiques from the scientific community.
Our concern here is that the Review transgresses medical law, policy, and practice, which puts it at odds with all mainstream U.S. expert guidelines. The report deviates from pharmaceutical regulatory standards in the United Kingdom. And if it had been published in the United States, where it has been invoked frequently, it would have violated federal law because the authors failed to adhere to legal requirements protecting the integrity of the scientific process.
The Review calls for evidentiary standards for GAC that are not applied elsewhere in pediatric medicine. Embracing RCTs as the standard, it finds only 2 of 51 puberty-blocker and 1 of 53 hormone studies to be high-quality. But more than half of medicines used in pediatrics have historically been prescribed off-label on the basis of limited evidence. Physicians have noted that requiring robust evidence for pediatric use of every drug would greatly limit drug treatments for children, who are already considered by researchers to be “pharmaceutical orphans.” Indeed, Cass has herself admitted that RCTs are probably infeasible in the GAC setting; “they’re difficult studies to design because you can’t blind people,” she notes, since patients will see bodily changes when given GAC-related pharmaceuticals.
Daniel G. Aaron and Craig Konnoth, “The Future of Gender-Affirming Care — A Law and Policy Perspective on the Cass Review,” New England Journal of Medicine 392, no. 6 (February 6, 2025): 526–528.
Cass Review commentary positions non-affirmative approaches as “neutral,” contrasting them to affirmative approaches that are framed as “ideological.” There is no recognition of the ideology underpinning approaches that deny the existence or validity of trans children. Cass Review reports do not consider the harms of approaches that deny or reject a trans child’s identity (…). Instead, Cass Review reports provide a sympathetic description of non-affirming professionals, centering the pressure they feel under to adopt an affirmative approach …
A significant indication of cisnormative bias can be seen in the absence of recognition of the existence of trans children across all Cass Review reports. A review expected to define best practices for trans children’s healthcare chooses to entirely avoid the word trans when referring to the children or adolescents who access UK Children’s Gender Services. Whilst including seven references to “transgender adults,” the interim report does not include even one reference to a trans child, adolescent or young person. Trans children are instead reduced to definition as “gender questioning children and young people” (Report 5, p. 11) or “children and young people needing support around their gender” (Report 5, p. 7). This framing conflates trans children, including those who have socially transitioned and are settled and confident in their affirmed identity, with children who are questioning their gender. This conflation erases the existence of trans children.
Cal Horton, “The Cass Review: Cis-Supremacy in the UK’s Approach to Healthcare for Trans Children,” International Journal of Transgender Health (March 14, 2024): 1–25.
When governments start weighing in on health care practice, the results are almost always terrible.
[… pause for dramatic effect …]
An independent review commissioned by the NSW government in the wake of a Four Corners story into gender-affirming care for children has found that puberty suppression treatment is still “safe, effective and reversible” but calls for more long-term quality research, acknowledging the strength of evidence is low.
Surprise! It turns out that if you approach the evidence in a fair and balanced manner, you wind up concluding gender-affirming care is generally A-OK. The Executive Summary has its own document, but I’d like to share detailed quotes from the full update.
As in the 2020 Evidence Check, the following clinical interventions were evaluated: two types of pharmaceutical intervention (puberty suppression and gender-affirming hormone therapy), surgical intervention (chest or breast surgery), and cryopreservation of gametes (sperm or oocytes). …
Broadly, the newly identified evidence reinforced the finding of the previous Evidence Check regarding benefits and effectiveness. That is, PS agents (generally referred to as GnRHa) were reported to be safe, effective and reversible. As a counterpoint, this update identified one study describing differential implications of PS for later surgery, with reduced need for mastectomy in trans men but potential complications for genital surgery in trans women as penile inversion may be compromised. Psychological effects of PS on conditions such as depression and anxiety appear modest in comparison with GAHT, with the primary impact being reduction of distress associated with unwanted secondary sexual characteristics; two Level IV studies reflected positive impacts on gender dysphoria.
With regard to risks and potential harms, reductions in bone density remain the primary concern with PS and monitoring of bone mineral density is recommended. However, some newly identified studies suggest maintenance of bone mineral density during PS treatment. Studies reported no indications to monitor liver or renal function in the PS setting. Other reported side effects of PS were also relatively minor. Instances of insufficient suppression of puberty (known as ‘pubertal escape’) were reported, but satisfaction with PS treatment was reported as good overall. …
The newly identified studies support the conclusions of the previous review, which reported that GAHT was effective in producing changes in body composition that align with the desired sex. Increases in BMI were reported; however, this remained in the healthy range and did not appear to be long term. There does not appear to be a significant impact on adult height and it appears that GAHT recovers the bone mineral density losses that occur during PS.
Additionally, there were mixed results on menstrual suppression (albeit in Level IV studies) with some studies reporting good achievement of amenorrhea and others reporting breakthrough bleeding. A number of studies provided new evidence pertaining to the psychological benefits of GAHT. The identified studies reported positive results across the domains of body image, gender dysphoria, depression, anxiety, suicide risk, quality of life and cognitive function. However, neutral and some negative findings were also reported in these domains. Additionally, two Level IV studies reported no changes in mental health care use following gender-affirming pharmaceutical care. Although studies reporting positive mental health outcomes following GAHT outnumber those with neutral or negative findings, considerable flaws remain in the evidence because of generally low participation rates of target groups, inadequate representation of young people and / or poor study designs and conduct. ….
Findings on overall safety, cardiometabolic risk, kidney and physiological parameters support the previous review’s findings that serious adverse outcomes associated with GAHT are rare. One Level I study flagged risk of meningioma associated with cumulative dose exposures of cyproterone acetate greater than 3g and therefore quoted recommendations that daily doses should be 10mg or less. This study also reported increased prolactinoma risk, which may reflect increased monitoring, with symptomatic prolactinoma risk not elevated. Minor changes in physiological parameters were reported, for example, blood pressure and elevated potassium—in the case of potassium, none of the subjects had symptoms of hyperkalaemia, and all elevated measurements were normal when repeated. Newly identified primary studies reported a range of less serious side effects (for example, headaches, nausea and vomiting), consistent with the previous review. There was some evidence regarding fertility impacts of GAHT, although only from two Level IV studies.
Note that I called this an “update” instead of a “report.” If you read carefully, you’ll have noticed the mention of a prior report completed five years ago that came to the same basic conclusions. While the evidence is still thin, there’s enough there to justify gender-affirming care to all transgender people, despite their age.
The French medical establishment agrees.
In a groundbreaking development for the care of transgender youth in France, the French Society of Pediatric Endocrinology and Diabetology has released what is being called the first French national medical consensus on trans youth care. …
The authors also refute suggestions in the Cass Review around negative impacts of transgender healthcare. For instance, the Cass Review in several occasions speaks of potential “loss of bone density” among trans youth taking puberty blockers. Instead, the French review notes that trans people have low bone densities regardless of treatment due to other factors: “Trans youth have an average BMD before the onset of puberty that is lower than that of the general population, regardless of treatment. This is probably related to the consequences of dysphoria: less physical activity, eating disorders, and/or poor dietary balance,” and they also note that after moving to gender affirming hormones, “BMD comparable to that of the experienced gender.” They also recommend vitamin D and exercise to mitigate potential concerns.
The group also explored suggestions found in the Cass Review that puberty blockers could harm brain development. On this subject, they found that “GnRHa treatments in transgender adolescents have no negative effect on the association between intellectual quotient and academic success nor on executive function performances.”
The full report is here, and contains detailed instructions for gender-affirming care that are free for everyone to read. I think I’ve thrown enough long quotes at you, but permit me this one short indulgence:
In the long term, there is limited data available [on the side-effects of puberty blockers]. Most of the knowledge comes from the experience of treating precocious puberty with GnRHa, which has a 40-year history and reassuring data.
François Brezin et al., “Endocrine Management of Transgender Adolescents: Expert Consensus of the French Society of Pediatric Endocrinology and Diabetology Working Group,” Archives de Pédiatrie (2024): S0929693X24001763.
If you only read the Cass Review, you’d have no idea that most children taking puberty blockers are cis, not trans.
“Puberty blockers have been used for decades in cisgender kids who either are going through puberty too early, or, in some instances, kids who are going through puberty very quickly,” Jason Klein, a pediatric endocrinologist and Assistant Director of the Transgender Youth Health Program at Hassenfeld Children’s Hospital at NYU Langone, told VICE. “Their use has been FDA approved, well-studied, well-documented, and well-tolerated for a long time now. And it’s the exact same medication that we use in trans or nonbinary children to basically put a pause on pubertal development. Exactly the same medications, at exactly the same doses.”
As a result almost no government actually bans puberty blockers, they just ban access to them for a minority of children. The only way you can justify that is if, like the Cass Review, you assume transgender children do not exist, and heavily distort the evidence while pretending to be “objective.”
I’ve been tempted to critique the Cass Review ever since it was released, but by now so many medical professionals have weighed in that I don’t see much point. The Review is not quite as bad as Wakefield’s infamous study, but then again the internal documents behind it have yet to be released to the public, plus the review was silently amended to make it even more contrary to the evidence. Dr. Cass is rapidly approaching the same level of quackery and harm to the general public.