Rational Thinking Revisited: The Cass Review

June 13, 2024 • Posted in Blog




Joyce A. Shelton, Ph.D.

Professor of Biology Emerita

Trinity International University



In April of this year, the National Health Service (NHS in the UK) released a long anticipated definitive report:  The Cass Review: Independent review of gender identity services for children and young people. Four years ago, seeking an evidence-informed way forward in the wake of rising controversy regarding the escalating prescription of puberty blockers, cross-sexualizing hormones and radical gender-altering surgeries for young children experiencing gender confusion, the NHS commissioned this comprehensive review headed by Hilary Cass. Dr. Cass is one of the most highly respected pediatric physicians in the UK with a storied, 30-year career in research, consulting and medical practice and having recently served as President of the Royal College of Pediatrics and Child Health. Her conclusions are based on extensive evidence gathered through analysis and quality assessment of numerous studies incorporated into eight systematic reviews,  surveys of fifteen gender clinics across Europe, and interviews with over 1,000 clinicians, patients and families. The Final Report  is excellently written, transparent, rigorous, reasonable in its approach and conclusions, rational and compassionate in its recommendations.  Because the review has already generated questions and controversy, a FAQs site has been made available. Whether or not one agrees with every aspect of this landmark report, it deserves to be taken seriously.

The most impactful of the findings address the massive over-prescription of puberty blockers and cross-sexualizing hormones to very young children. The Cass Review found the research regarding their use in treating gender questioning youth to be either nonexistent or of such poor quality as to render it useless for clinical decision-making. Furthermore, the efficacy and safety of these drugs have been widely overstated and/or misrepresented. There exists no knowledge regarding potentially harmful, long-term effects of puberty blockers on physical, cognitive or psychosocial development and they have no proven benefits for treating gender distress/incongruence.  Likewise, long-term outcomes are unknown for cross-sexualizing hormones. There are hardly any follow-up data on those who have been treated with them.  Cass has commented that “the real problem is that the evidence is very weak compared to many other areas of pediatric practice….I can’t think of any other situation where we give life-altering treatments and don’t have enough understanding about what’s happening to those young people in adulthood.” Her report concludes that puberty blockers should only be used to treat abnormal precocious puberty and should not otherwise be prescribed to patients under 18. The rare exception would be if they are participants in a supervised, randomized controlled clinical trial where vulnerable subject protections are in place. Indeed, more such responsible research is needed. Extreme caution is also recommended in prescribing cross-sexualizing hormones to children under 18.  The report also acknowledged that young children may or may not continue with a trans-identity and, thus, their clinical presentation may be due to multiple factors that necessitate a comprehensive evaluation and individualized care plan.  A medical solution may not be the best way to treat their gender distress.  Naysayers have intimated that withholding such medical treatment is discriminatory against trans-persons.  Cass has countered that “this review is not about trans youth. This is about children with a complex range of conditions, of which gender questioning is one part, and how we provide a holistic service to support their well-being.”

The Cass Review begins the journey back to rational, consistent application of evidence-based, safe medical treatments and individualized whole person care, which, to the detriment of our children, has been largely abandoned in this particular area of medicine in favor of ideology and politics driven approaches. The recommendations are already being used across the UK to mandate more cautious treatment. In the US, however, “gender-affirming care” has been strenuously endorsed and promoted by politicians, health care professionals, self-appointed “experts”, and a surfeit of three-letter organizations (e.g. AAP, AMA, APA, HHS, DOE) not to mention the White House.  Cass described these groups as an “echo chamber,” saying there is “circularity in their guidance.” Consequentially and sadly, thus far, in the US, there has been much less acceptance of the Cass Review and no immediate changes in these harmful care protocols.  In an interview with the NY Times, Cass extended professional courtesy to the American Academy of Pediatrics (AAP), one of the most adamant medical advocates of child gender transitions in the US,  but she stated that she “respectfully [disagrees] with them on holding to a position that is now demonstrated to be out of date by multiple systematic reviews.”  Cass also stressed that “medicine should never be politically driven. It should be driven by evidence and ethics and shared decision-making with patients and listening to patients’ voices. Once it becomes politicized, then that’s seriously concerning, as you know well from the abortion situation in the United States.” Throughout her report and in multiple interviews, Cass has repeatedly emphasized that the real subjects for concern here are the countless vulnerable children whose lives may have been permanently devastated by receiving experimental treatments with no medically verified basis nor benefit. Continuing down this scientifically indefensible wormhole is intellectually and morally unconscionable. The Cass Review provides a strong basis and means for the US medical community to revisit rational thinking, reverse course, and return to their core ethical principle, do no harm.

Note: On June 8, 2024 the American College of Pediatricians held a press conference and released a statement calling for medical professional organizations to “immediately stop the promotion of social affirmation, puberty blockers, cross-sex hormones and surgeries for children and adolescents who experience distress over their biological sex.” (Full statement here).


The Tennessee Center for Bioethics & Culture encourages respectful discussion and debate of bioethics issues, and strongly supports freedom of speech. To that end, we invite and welcome other voices to the discussion of bioethics issues. Invited authors’ views are their own, and do not necessarily represent those of The Tennessee Center for Bioethics & Culture.