This informal CPD article ‘Qualifying conditions for medical cannabis in the UK (2026)’ was provided by Dr Sue Clenton, Medical Director and Consultant Oncologist at Releaf, a HealthTech company dedicated to transforming access to Cannabis Based Products for Medical use (CBPMs) in the UK.
In clinics, a question from patients that seems to be surfacing more often in recent months than in previous years is “Can cannabis suppress tumour growth?”. This claim is nothing new and one that Oncologists have heard for years: cannabinoids shrink tumours. And while the science behind such bold claims is certainly not 100% imaginary, there is a long way to go before any sort of concrete claims can, or should, be made.
Let’s be crystal clear here - at present, cannabinoids cannot be considered anti-tumour treatments. The current evidence that suggests that any form of cannabis-based medicine can actually suppress cancer tumour growth comes from laboratory work involving cell cultures and animal models rather than large, well-designed human trials [1]. That is not to say that medical cannabis treatment should never be considered for patients with cancer, just that it is not a cure for the disease itself.
What the research actually shows
The endocannabinoid system was first described in 1988 and is now recognised as a widespread neuromodulatory network across the body [2]. It regulates signalling across much of the human body and is present in both the central and peripheral nervous systems.
It involves CB1 and CB2 receptors, endogenous ligands, and enzymes that control synthesis and breakdown. These receptors are present in some tumour types. Gliomas, for example, often show increased cannabinoid receptor expression [1].
The potential that cannabinoids have shown as anti-tumour agents largely stems from preclinical research. Preclinical studies are laboratory or animal experiments conducted before research moves into human trials.
A wide-ranging review summarised studies across glioma, breast, lung, pancreatic, prostate, and melanoma models. In those controlled settings, cannabinoids such as THC and CBD have been linked to slower tumour cell growth, increased cancer cell death, and, in some cases, reduced development of the blood vessels that feed tumours. These findings are scientifically interesting, but they remain early-stage and have not yet been translated into robust clinical evidence [1].
Cannabis in supportive cancer care
Medical cannabis is already able to be legally prescribed here in the UK to help manage some of the side effects of certain conventional cancer treatments and to help reduce the impact of cancer's secondary symptoms. There is already evidence supporting their role in reducing nausea and vomiting, improving appetite, and helping with cancer-related pain. Many patients also describe better sleep and less treatment-related anxiety and/or depressive issues when symptoms are better controlled [3,4].
Since 2018, medical cannabis has been a legal treatment option in the UK for recognised problems such as cancer-related pain, severe nausea, poor appetite, and persistent sleep disruption. The aim is practical: reduce the physical burden of treatment and help patients function day to day, particularly when first-line options have not been enough. There is also the mental heaviness that so often goes hand in hand with a cancer diagnosis. Ongoing, long-term treatment comes with a level of uncertainty that can be extremely hard to handle.
And then there are the repeated scans, bouts of chemotherapy or radiotherapy, disrupted sleep, and persistent pain, all of which take a psychological toll. When symptoms are better controlled, many patients report reduced anxiety and improved mood. That does not remove the diagnosis, but it can make living with it more manageable.
A patient who is sleeping more consistently and able to maintain a consistent diet full of nutritious options is often better equipped to cope with the demands of ongoing treatment. Symptom control does not change the biology of the tumour, but it can make the process of treatment more tolerable and, in many cases, more sustainable.
Final thoughts
Throughout the past decades, far too often cancer care has focused more on suppressing tumour growth than on also helping patients with the huge toll that both the symptoms and the treatment options can and do take. Symptom control and tumour-directed treatment both have different aims, but they should not be seen as mutually exclusive. Supporting a patient through treatment, including when medical cannabis forms part of that support, sits within comprehensive cancer care.
So, to return to the main question - “Can medical cannabis treatment suppress tumour growth?” - Right now, the answer is a firm no. But it can be expected to see more research emerging in the very near future based on human trials.
We hope this article was helpful. For more information from Releaf, please visit their CPD Member Directory page. Alternatively, you can go to the CPD Industry Hubs for more articles, courses and events relevant to your Continuing Professional Development requirements.
References
- Cherkasova V, Wang Y, Gerasymchuk M, et al. Use of cannabis and cannabinoids for the treatment of cancer. Cancers (Basel). 2022;14(20):5142. doi:10.3390/cancers14205142
- Lu HC, Mackie K. An introduction to the endogenous cannabinoid system. Biol Psychiatry Cogn Neurosci Neuroimaging. 2021;6(6):607–615. doi:10.1016/j.bpsc.2020.09.005
- Bar-Lev Schleider L, Mechoulam R, Lederman V, et al. Prospective analysis of safety and efficacy of medical cannabis in large unselected population of patients with cancer. Eur J Intern Med. 2018;49:37–43. doi:10.1016/j.ejim.2018.01.023
- Boland EG, Bennett MI, Allgar V, Boland JW. Cannabinoids for adult cancer-related pain: systematic review and meta-analysis. BMJ Support Palliat Care. 2020;10(1):14–24. doi:10.1136/bmjspcare-2018-001753
