Cannabis, cannabinoids and cancer – the evidence so far
The current consensus is that, right now, there isn’t a large enough body of evidence to prove that cannabis (or any of its active compounds or derivatives) can reliably treat any form of cancer but the medical use of cannabis to treat cancer-related chronic pain is approved in the UK.
Cancer Research UK does not have an organisational policy on the legal status of cannabis, its use as a recreational drug, or its medical use diseases other than cancer. But we are supportive of properly conducted scientific research into cannabis and its derivatives that could benefit cancer patients and we will continue to monitor developments in the fields and evidence as it emerges.
For the last couple of decades, one of the most talked about discussions online is whether or not cannabis can treat cancer.
Claims that there is solid “proof” that cannabis or cannabinoids can cure cancer are highly misleading. Unfortunately, there are many unreliable sources of information about cannabis, particularly online.
This post contains up-to-date, evidence-based information on cannabis and cancer.
What is cannabis?
Cannabis is a plant grown and cultivated commercially across the globe. It is known by many names depending on its preparation and quality, including marijuana, trees, pot, dank, grass, green, kush, weed, hemp, hash, loud, and herb. These usually refer to the dried form or resin of the flowers or leaves of the plant.
There are multiple species of cannabis plant, including Cannabis sativa, Cannabis indica and Cannabis ruderalis.
For thousands of years, it has been used recreationally, religiously, and medically. Records from Ancient Egypt, India, and China show that physicians would use the plant as part of treating ailments such as haemorrhoids, insomnia, and for other pain relief.
In the Western world, cannabis emerged as a mainstream medicine in the 1840s and was noted for its sedative, anti-inflammatory, pain relief, and anticonvulsant effects.
Scientists have identified multiple active compounds within cannabis (known as cannabinoids) that play a role in cannabis’ effects, including the psychoactive delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).
Cannabinoids – what are they?
Cannabinoids are compounds that can interact with a system inside the body known as the endocannabinoid system.
Most commonly, the term “cannabinoid” is used to refer to the compounds found in cannabis (and other plants). As the body naturally produces cannabinoids itself (known as endocannabinoids), a more accurate term for these is phytocannabinoids (meaning “cannabinoids from plants”).
Researchers have found that cannabis contains over 450 different chemical compounds, many of which are cannabinoids.
The two main cannabinoids of interest to researchers are:
- Delta-9-tetrahydrocannabinol (THC) – a psychoactive substance that can affect how the brain works, creating a ‘high’ feeling.
- Cannabidiol (CBD) – may relieve pain, lower inflammation and decrease anxiety without any psychoactive effects.
Is cannabis legal in the UK?
In the UK, medical use of cannabis was legalised in November 2018 and the UK is one of the world’s largest exporters of legal cannabis. However, cannabis is still classified as a class B drug in the UK, meaning that it is illegal to possess or supply it for personal recreational use.
- Products without THC – legal to buy in the UK as supplements (such as CBD oil or hemp oil).
- Products containing THC – illegal in the UK for recreational purposes (such as cannabis flower, cannabis oil, edibles, etc).
- Medicines derived from cannabis – legal in the UK for certain healthcare professionals to prescribe (such as Sativex and Nabilone).
Medical cannabis is only legal when prescribed by a specialist consultant and GPs are not allowed to prescribe cannabis-derived medicines. NHS guidance states that medical cannabis should only be prescribed when there is clear published evidence of its benefit and other treatment options have been exhausted.
How do cannabinoids work inside the body?
Our bodies naturally produce our own cannabinoids (known as endocannabinoids).
These interact with molecules found on the surface of cells (cannabinoid receptors). One type of is densely packed inside the brain and second type is found in our immune tissues.
These compounds and receptors form the endocannabinoid system, a network that is involved in the control and regulation of multiple functions within the body – including memory, sleep, learning, eating, pain control, inflammation, and immune system.
As THC, CBD and other cannabinoids look similar to the endocannabinoids inside the body, they are able to interact with these receptors and affect how the system functions.
This is why some researchers think that cannabinoids have the potential to control some of the most common and debilitating symptoms of cancer and its treatments, including nausea and vomiting, loss of appetite, and pain.
Is all cannabis is the same?
Like how beer, wine, and vodka all have differing levels of alcohol and other ingredients, different strains/types of cannabis have varying levels of THC, CBD, and other compounds. This means that different strains of cannabis can have different effects on the body.
Additionally, its effects also depend on how cannabis is taken, most commonly by inhaling (smoking or vaping) or ingesting (edibles).
When it is inhaled, THC enters the lungs where it passes directly into your bloodstream and then your brain quickly. The effects of inhaled cannabis fade faster than cannabis taken by mouth.
When ingested (such as when it’s used in oils/drinks/baked goods/sweets), edible cannabis travels first to your stomach then to your liver before getting into your bloodstream and brain. The liver converts THC into a stronger compound and this (combined with the THC from the original product) adds to the intensity of the high.
Are there cannabis-based medicines?
Some cannabis-based products are available on prescription. The following medicines are sometimes prescribed to help relieve symptoms.
Nabilone is a drug developed from cannabis. It is licensed for treating severe sickness from chemotherapy that is not controlled by other anti-sickness drugs.
It works very well for some people, but can cause drowsiness or dizziness in others. These side effects can last for a couple of days after you’ve stopped taking it.
Sativex (or nabixmols) is a liquid cannabis-based medicine that you spray into your mouth.
Researchers are looking into Sativex as a treatment for cancer related symptoms and for certain types of cancer.
Is Cancer Research UK investigating cannabinoids?
In the past, Cancer Research UK has funded research into cannabinoids, notably the work of Professor Chris Paraskeva in Bristol investigating the properties of cannabinoids as part of his research into the prevention and treatment of bowel cancer. He has published a number of papers detailing lab experiments looking at endocannabinoids as well as THC, and written a review looking at the potential of cannabinoids for treating bowel cancer.
We have also supported the work of Dr Laureano de la Vega , a Cancer Research UK Fellow at the University of Dundee, who in 2019 started to explore if CBD can limit cancer’s ability to spread, using lung and triple negative breast cancer cells grown in the lab.
We’re also involved in the only 2 UK clinical trials of cannabinoids for treating cancer, mentioned above, through our national network of Experimental Cancer Medicine Centres .
Our funding committees have previously received other applications from researchers who want to investigate cannabinoids but these failed to reach our high standards for funding.
If we receive future proposals that meet these stringent requirements, then there is no reason that they wouldn’t be funded, assuming we have the money available.
Unfortunately, some scammers are using the email address [email protected] and claiming to be based at our head office, tricking cancer patients and their families into handing over money for “cannabis oil”, after which they receive nothing in return. This is a scam and has nothing to do with Cancer Research UK or our employees, as we wrote about in 2015. If you believe you have been a victim of this fraud, please contact the police.
How do researchers study cannabis?
Around the world, many researchers are actively investigating cannabis and cannabinoids, and Cancer Research UK is supporting some of this work.
Generally, the cannabis that researchers study isn’t the same as the one as you might see on the street or oils sold in shops.
When researchers conduct rigorous scientific studies, they often use purified forms of the compounds that they are investigating . This gives us more reliable evidence on the effect of different cannabinoids.
Through many detailed experiments – summarised in this review article from the British Journal of Cancer – scientists have discovered that both natural and synthetic cannabinoids have a wide range of effects on cells, which is why there’s interest in finding out whether it can be a part of treating diseases like cancer, as well as help relieving side effects.
Can cannabinoids treat cancer?
As of 2022, several hundreds of scientific papers looking at cannabinoids, the endocannabinoid system, and the relation to cancer have been published. So far these studies simply haven’t found enough robust scientific evidence to prove that these can safely and effectively treat cancer.
This is because the majority of the scientific research investigating whether cannabinoids can treat cancer has been done using cancer cells grown in the lab or animals. While these studies are a vital part of research, providing early indications of the benefits of particular treatments, they don’t necessarily hold true for people.
Much of the research into cannabinoids and cancer so far has been done in the lab
So far, the best results from lab studies have come from using a combination of highly purified THC and CBD . But researchers have also found positive results using man-made cannabinoids, such as a molecule called JWH-133.
There have been intriguing results from lab experiments looking at a number of different cancers, including glioblastoma brain tumours, prostate, breast, lung, and pancreatic cancers. But the take-home message is that different cannabinoids seem to have different effects on various cancer types, so they are far from being a ‘universal’ treatment.
There’s also evidence that cannabinoids have unwanted effects. Although high doses of THC can kill cancer cells, they also harm crucial blood vessel cells. And under some circumstances, cannabinoids can encourage cancer cells to grow, or have different effects depending on the dose used and levels of cannabinoid receptors present on the cancer cells.
Cannabis in clinical trials
To robustly test the potential benefits of cannabinoids in cancer, clinical trials in large numbers of people with control groups of patients – who aren’t given the treatment in question – would be needed.
A few small clinical trials have been set up to test the benefits of cannabinoids for people with glioblastoma multiforme. Results published from a pilot clinical trial where 9 people with advanced, incurable glioblastoma multiforme – the most aggressive brain tumour – were given highly purified THC through a tube directly into their brain showed that THC given in this way is safe and doesn’t seem to cause significant side effects. But as this was an early stage trial without a control group, it couldn’t show whether THC helped to extend patients’ lives.
And a second clinical trial, supported through our Experimental Cancer Medicine Centre (ECMC) Network, tested whether Sativex (nabiximols), a highly purified pharmaceutical-grade extract of cannabis containing THC, CBD, and other cannabinoids could treat people with glioblastoma multiforme brain tumours that have come back after treatment.
In 2021, scientists reported the final results of this phase 1 study to treat people with recurrent glioblastoma with Sativex in combination with the chemotherapy drug, temozolomide. Researchers found that adding Sativex (patients were allowed to choose the amount they took) had acceptable levels of side effects, which included vomiting, dizziness, fatigue, nausea and headache. They also observed that more patients were alive after one year using Sativex (83%) compared to those taking the placebo (44%). However, this phase 1 study only involved 27 patients, which was too small to confirm any potential benefits of Sativex, and was intended to find out if it was safe to take by patients.
This trial is being extended into phase 2 (known as ARISTOCRAT) to explore if this treatment is effective and which patients are most likely to respond to this treatment. It is set to launch at 15 NHS hospitals in 2022, with over 230 patients to be recruited (and making use of the Cancer Research UK Clinical Trials Unit). To find out more about this work, you can listen to our podcast – That Cancer Conversation – where we hear from Professor Susan Short, one of the researchers leading this study.
We’ve also supported a trial that’s testing the benefits of a man-made cannabinoid called dexanabinol in patients with different types of advanced cancer. The trial finished recruiting in 2015 and researchers established a safe dose of the drug, but further development of the drug was stopped due to a lack of evidence around the drug’s effectiveness. Full trials results are yet to be published.
Groups exploring cannabinoids and cancer
is researching cannabis and cannabinoids for treating cancer to build up the evidence. He is happy to collect individual stories from UK patients and can be contacted by email. is the lead on the ARISTOCRAT trial that is evaluating the combined use of Sativex and the chemotherapy drug temozolomide treat people with recurrent glioblastoma.
- The Medical Cannabis Research Group at Imperial College London are exploring cannabinoid use as it relates to potential therapies for inflammation and pain linked to cancer.
- The charity DrugScience are running Project Twenty21, an observational medical cannabis study in the UK. It is gathering data on the efficacy of cannabis-based medicines for a wide range of conditions (including cancer-related pain, nausea, and anxiety).
Can cannabis prevent cancer?
There is no reliable evidence that cannabis can prevent cancer.
There has been some research suggesting that the body’s endocannabinoids (mentioned earlier) can suppress tumour growth.
When it comes to cannabis, experiments where mice were given very high doses of purified THC showed that they seemed to have a lower risk of developing cancer. But this is not enough solid scientific evidence to suggest that cannabinoids or cannabis can cut people’s cancer risk.
Does cannabis cause cancer?
The evidence is a lot less clear when it comes to whether cannabis itself can cause cancer.
This is because most people who use cannabis smoke it mixed with tobacco, a substance that we know causes cancer. Data from 2016 has shown that 77% of UK people surveyed (who smoke weed) reported normally mixing it with tobacco.
This makes it hard for researchers to disentangle the potential impact of cannabis on cancer risk from the impact of the tobacco. As of 2022, we can’t be sure whether the increased risk is due to tobacco or whether cannabis itself also has an independent effect.
We do know from decades of evidence that there is no safe way to use tobacco – it’s addictive and harmful for your health. People who smoke weed mixed with tobacco increase their risk of cancer and other conditions. Tobacco also contains the very addictive substance nicotine. This means people who regularly smoke weed mixed with tobacco may find it harder to stop.
In addition to this, there have not been published studies looking at cannabis ingestion (such as edibles) and cancer risk, nor vaporised cannabis and cancer risk.
> Read about the free support and quitting tools available to help you to stop smoking for good on our website.
Can cannabis relieve cancer symptoms like pain or sickness?
There’s good evidence that cannabinoids may be beneficial in managing cancer pain and side effects from treatment.
As far back as the 1980s, cannabinoid-based drugs including dronabinol (synthetic THC) and nabilone were used to help reduce nausea and vomiting caused by chemotherapy. But there are now safer and more effective alternatives and cannabinoids tend to only be used where other approaches fail.
In some parts of the world, medical marijuana has been legalised for relieving pain and symptoms (palliative use), including cancer pain. But one of the problems with using herbal cannabis is managing the dose. Smoking cannabis or taking it in the form of tea often provides an inconsistent dose, which may make it difficult for patients to monitor their intake. So, researchers are turning to alternative dosing methods, such as mouth sprays, which deliver a reliable and regulated dose.
Large-scale clinical trials in the UK have been testing whether a mouth spray formulation of Sativex (nabiximols) can help to control severe cancer pain that doesn’t respond to other drugs. Results from these didn’t find any difference in self-reported pain scores between the treatment and the placebo.
Cannabinoids may also have potential in combating the loss of appetite and wasting (cachexia) experienced by some people with cancer, although so far clinical evidence is lacking. One clinical trial comparing appetite in groups of cancer patients given cannabis extract, THC and a placebo didn’t find a difference between the treatments, while another didn’t show any benefit and was closed early.
Questions that still need to be answered
There are still many unanswered questions around the potential for using cannabinoids to treat cancer. It’s not clear:
- which type of cannabinoid – either natural or synthetic – might be most effective
- what kind of doses might be needed
- which types of cancer might respond best to cannabinoids
- how to avoid the psychoactive effects of THC
- how best to get cannabinoids, which don’t dissolve easily in water, into cancer cells
- whether cannabinoids will help to boost or counteract the effects of chemotherapy
These questions must be answered for cannabinoids to be used as safe and effective treatments for cancer patients. It’s the same situation for the many hundreds of other potential cancer drugs being developed and tested in university, charity and industry labs all over the world.
Without doing rigorous scientific research, we will never sift the ‘hits’ from the ‘misses’. If cannabinoids are to get into the clinic, these hurdles first need to be overcome and their benefits proven over existing cancer treatments.
Frequently asked questions (FAQs)
“What’s Cancer Research UK’s view on cannabis and cancer?”
As of 2022, Cannabis is still classified as a class B drug in the UK, meaning that it is illegal to possess or supply it for personal recreational use.
Cancer Research UK does not have an organisational policy on the legal status of cannabis, its use as a recreational drug, or its medical use in any other diseases.
But we are supportive of properly conducted scientific research into cannabis and its derivatives that could benefit cancer patients and we will continue to monitor developments in the fields and evidence as it emerges.
“It’s natural so it must be better, right?”
There’s no doubt that the natural world is a treasure trove of biologically useful compounds, and there are countless examples where these have been harnessed as effective treatments.
Numerous potent cancer drugs have also been developed in this way – purifying a natural compound, improving it and testing it to create a beneficial drug – including taxol, vincristine, vinblastine, camptothecin, colchicine, and etoposide.
But although these purified drugs in controlled high doses can treat cancer, it doesn’t mean that the original plant (or a simple extract) will have the same effect.
So, although cannabis contains certain cannabinoids, it doesn’t automatically follow that cannabis itself can treat cancer.
“But it worked for this patient…”
Doctors sometimes publish case reports about extraordinary or important observations they have seen in their clinic.
For example, there was a case report published in the British Medical Journal describing a woman in her 80s with lung cancer whose tumour shrank after taking CBD oil over several months.
This might seem like a solid bit of proof, but very little reliable information can be taken from a single patient treated with what’s an unknown mix of cannabinoids outside of a controlled clinical setting
The authors state that even though this case appears to demonstrate a possible benefit of CBD oil intake, it’s not possible to confirm that the tumour regression was due to the patient taking CBD oil (as she was also taking drugs for other conditions).
There are also many videos and anecdotes online claiming that people have been completely cured of cancer with cannabis, hemp/cannabis oil or other cannabis derivatives.
Despite what these sources may claim, it’s impossible to tell whether these patients have been ‘cured’ by cannabis or not. There is usually no information about their medical diagnosis, stage of disease, what other cancer treatments they had, or the chemical make-up of their treatment. These sources also only publish the “success stories”, and don’t share how many people who used cannabis or its derivatives had no benefit, or worse, were potentially harmed.
Robust scientific studies describe the detail of experiments and share the results – positive or negative. This is vital for working out whether a potential cancer treatment is truly safe and effective, or not. And publishing this data allows doctors around the world to judge the information for themselves and use it for the benefit and safety of their patients.
This is the standard to which all cancer treatments are held, and it’s one that cannabis and cannabinoids should be held to, too.
“What’s the harm? There’s nothing to lose.”
If someone chooses to complete reject conventional cancer treatment in favour of unproven alternatives, they may miss out on treatment that could save or significantly lengthen their life. They may also miss out on effective symptom relief to control pain or other problems.
Many unproven therapies are also expensive, and aren’t covered by the NHS or medical insurance. In the worst cases, an alternative therapy may even hasten death.
Although centuries of human experimentation tell us that naturally-occurring cannabinoids are broadly safe, they are not without risks. They can increase heart rate, which may cause problems for patients with pre-existing or undiagnosed heart conditions. They can also interact with other drugs in the body, including antidepressants and antihistamines. And they may also affect how the body processes certain chemotherapy drugs, which could cause serious side effects.
As cannabis is illegal for recreational use in the UK, there are further risks associated with using home-made preparations, particularly cannabis oil, such as toxic chemicals left from the solvents used in the preparation process.
Synthetic cannabinoids (sometimes known as spice) are compounds that have been designed to act like the chemicals found in cannabis but with far stronger effects and have harmful side-effects associated.
There are also many internet scams by people offering to sell cannabis preparations. As well as the risk of getting something with completely unknown chemical or medicinal properties and unknown effectiveness, scammers are tricking cancer patients and their families into handing over money for “cannabis oil” which they then never receive.
We understand the desire to try every possible avenue when conventional cancer treatment fails. But there is little chance that an unproven alternative treatment bought online will help, and it may well harm. We recommend that cancer patients talk to their doctor about clinical trials that they may be able to join, giving them access to new drugs in a safe and monitored environment.
“Are cancer charities hiding cannabis as a cure?”
The idea that a cure already exists is one of the many myths that surrounds cancer that we have written about.
This myth is unjust to the thousands of scientists, doctors and nurses working as hard as they can to beat cancer, and to the many thousands of people in the UK and beyond who give up their time and money to fund our work.
History shows that the best way to beat cancer is through rigorous scientific research. This approach has helped to change the face of cancer prevention, diagnosis, treatment, leading to increased survival in the last few decades .
As a research-based organisation, we want to see reliable scientific evidence to support claims made about any cancer treatment, be it conventional or alternative. This is vital because lives are at stake. Some people may think that a cancer patient has nothing to lose by trying an alternative treatment, but there are big risks.
“Big Pharma can’t patent it so they’re not interested.”
Some people argue that the potential of cannabinoids is being ignored by pharmaceutical companies, because they can’t patent the chemicals naturally occurring in cannabis plants. But there are many ways that these compounds can be patented – for example, by developing more effective lab-made versions or better ways to deliver them.
Other people argue that patients should be treated with homegrown cannabis preparations, and that the research being done by companies is solely to make money and prevent patients accessing “the cure”
The best chance of ensuring that the potential benefits of cannabinoids – whether natural or man-made – can be brought to patients is through research using quality-controlled, safe, legal, pharmaceutical grade preparations containing known amounts of the drugs.
This requires time, effort and money, which may come from companies or independent organisations such as charities or governments. And, ultimately, this investment needs to be paid back by sales of a safe, effective new drug.
It’s true that there are issues around drug pricing and availability and we’re pushing for companies to make new treatments available at a fair price. We would hope that if cannabinoids were to be shown to be safe and effective enough to make it to the clinic, they would be made available at a fair price for all patients who might benefit from them.
Right now, there simply isn’t enough evidence to prove that cannabinoids – whether natural or synthetic – can effectively treat cancer in patients, although research is ongoing. And there’s certainly no evidence that cannabis bought on the street can treat cancer.
We’re supportive of properly conducted scientific research into cannabis and its derivatives that could benefit cancer patients. Many researchers are actively exploring this approach, and Cancer Research UK is supporting, and will continue to support, scientifically robust research into cannabis and cannabinoids that reaches the high-quality standards set by our funding committees.
References and further reading:
- Cancer Research UK – Cannabis, CBD oil and cancer
- NHS – Medical cannabis (and cannabis oils)
- National Cancer Institute (US) – Information about cannabis and cannabinoids for cancer patients
- National Cancer Institute (US) – Information about cannabis and cannabinoids for health professionals
- Velasco, G., Sánchez, C. & Guzmán, M. (2012). Towards the use of cannabinoids as antitumour agents, Nature Reviews Cancer, 12 (6) 444. DOI: 10.1038/nrc3247
- Sarfaraz, S. et al (2008). Cannabinoids for Cancer Treatment: Progress and Promise, Cancer Research, 68 (2) 342. DOI: 10.1158/0008-5472.CAN-07-2785
- Guindon, J. & Hohmann, A.G. (2011). The endocannabinoid system and cancer: therapeutic implication, British Journal of Pharmacology, 163 (7) 1463. DOI: 10.1111/j.1476-5381.2011.01327.x
- Engels, F.K. et al (2007). Medicinal cannabis in oncology, European Journal of Cancer, 43 (18) 2644. DOI: 10.1016/j.ejca.2007.09.010
- Twelves, C., Sabel, M., Checketts, D. et al (2021). A phase 1b randomised, placebo-controlled trial of nabiximols cannabinoid oromucosal spray with temozolomide in patients with recurrent glioblastoma. British Journal of Cancer 124, 1379–1387. DOI: 10.1038/s41416-021-01259-3
- Cannabinoids in the treatment of chemotherapy-induced nausea and vomiting – Todaro (2012) Journal of the National Comprehensive Cancer Network
- Bowles, D.W. et al (2012). The intersection between cannabis and cancer in the United States, Critical Reviews in Oncology/Hematology, 83 (1) 10. DOI: 10.1016/j.critrevonc.2011.09.008
- Hall, W., Christie, M. & Currow, D. (2005). Cannabinoids and cancer: causation, remediation, and palliation, The Lancet Oncology, 6 (1) 42. DOI: 10.1016/S1470-2045(04)01711-5 . , Wai Liu, The Conversation – University of Birmingham
- Nutt D, Bazire S, Phillips LD, et al (2020) So near yet so far: why won’t the UK prescribe medical cannabis? BMJ Open 10:e038687. DOI: 10.1136/bmjopen-2020-038687
- Mangal, N., Erridge, S., Habib, N., Sadanandam, A., Reebye, V., & Sodergren, M. H. (2021). Cannabinoids in the landscape of cancer. Journal of cancer research and clinical oncology, 147(9), 2507–2534. DOI: 10.1007/s00432-021-03710-7
As a terminal liver cancer patient at the age of 31 I would try anything at this point as I have nothing else to loose. I don’t know why a significant amount of research hasn’t taken place as of yet when it should be done, even if it can help some patients and not all. It’ should be tested and given as a choice. The fact that we can not easily access it either is terrible yes it may not be a cure but it may help in some way and that’s the most important for cancer patients suffering
Thank you for most informative update. It’s a subject I’m most interested in and feel sure that the natural plant can produce some amazing results.
Until you’re a terminal cancer patient you just wont understand the desperation to live as long as possible, even if it were mere days extra time. I would try anything for extra time with loved ones.
I can’t believe there isn’t more research into cannabis and cancer. And for those that say “well it doesn’t work for everybody” guess what conventional cancer treatment doesn’t either.
Stage 4 cancer = no cure, terminal in most cases.
Why is it that charities raking in millions every year can find the evidence of cannabis for not treating cancer but cant find the overwhelming evidence that it can and does treat cancer ?
Great reading I have lung cancer I’m being treated with chemo now and would be interested in a trail it’s small cell lung cancer
Without full spectrum cannabis oil my life around a year into breast cancer I doubt I would be here now
It has enabled me to come off opioids and live a semi normal life
It sickens me to think drs happily give out meds that are killing people but won’t give out a herb that has O deaths yes Zero
I have even contacted professor Mike barns pleading with him to help me find a trial but guess what not one in the uk
The fact cannabis is illegal in this county is all political and NOTHING to do with our health
It’s about time charity’s like yours start campaigning for us, most of us medical cannabis users are spending far to much on it in order to feel well I echo what another commenter said that all stage 4 should be at least offered cannabis as an alternative
Also why can’t the hospital doctors give medical cannabis too relieve sickness and pain of cancer it’s cruel
I think that medical cannabis should be given too all stage 4 cancer patients that are told it’s aggressive and treatment wont help under medical care it could be done safely then with trial an error they will know if it works legalise cannabis for the sick wake up Boris
Thank you for sharing this amazing blog. It is easy to learn and understand. It’s a truly useful blog.
“Why don’t you campaign for cannabis to be legalised?” Your answer was ridiculous that’s all you said was that it’s illegal to possess or buy or what ever I think the question was why won’t you campaign to have it legal so then it can be tested more . Don’t beat around the bush ( No pun intended) just say it’s not worth the effort for the money you would have to spend .
this blog post is very perfect and has a lot of very vital info, thanks so much for this work
We’ve recently seen stories in the press claiming that the US government has “admitted that cannabis kills cancer” (for example, this one in the Metro), based on the observation that pages on the US National Cancer Institute information website carry details of the current scientific evidence around the effects of cannabis and cannabinoids on cancer cells in the lab and animal models.
The first thing to point out is that the NCI’s cancer information website is an independent resource for doctors and the patients, and is not a statement of NIH, NCI or US government policy.
Furthermore, the information on these pages isn’t new, nor is it an ‘admission’ of any kind: the scientific evidence about cannabis, cannabinoids and cancer, which these media stories are referring to, has been openly published on the NCI’s website for several years – for example, see this page from the same section of the NIH website on cannabis and cannabinoids from 2011, accessed via the internet archive.
We often see websites with long lists of scientific papers claiming that cannabis is a “cure” for various cancers. However, when we look at the detail of the data and the experimental detail of the research, it becomes clear that although they may be interesting and build evidence to show that cannabinoids may one day bring benefits for cancer patients, they are far from being a cure.
The main point to realise is that virtually all these studies have been done in cancer cells grown in the lab or in animals. These are quite artificial systems and are much less complex than a real cancer growing in a patient.
For example, most experiments with cells grown in the lab use cancer cells that were originally taken from a tumour many years ago, but have been grown for a long time in the lab – known as cell lines. One problem with such cells is that they are all very similar on a genetic and molecular level, but we know that in real cancers, the cells can be very different from each other and respond in different ways to treatments. Also the usual way of testing cannabinoids in animals has been done by transplanting cancer cells (either mouse or human) into mice. Usually only a small number (5-20) will be used for each experiment.
There’s growing evidence that these particular kinds of models (known as xenografts) aren’t as good at suggesting a treatment could work, compared to more sophisticated genetically engineered animals, as they don’t accurately represent the situation in real tumours. So although these kinds of experiments can point towards useful approaches, as well as revealing the underlying molecular ‘nuts and bolts’ of what’s going on, they can’t tell us if something will definitely treat cancer effectively and safely in human patients. They do not “prove that cannabis cures cancer”, as the headlines would have us believe.
Put simply, Petri dishes are not people. Most chemicals that show promise in lab or animal experiments turn out not to work as well as hoped when tested in patients. These kinds of human studies, known as clinical trials, are the only way we can really know if a cancer treatment is effective. There’s more about clinical trials on our website: http://www.cancerresearchuk.org/cancer-help/trials/types-of-trials/
It’s also important to think about what’s being claimed when people use the word “cure”. To most people, including us, this means that a cancer is completely treated and does not come back. When we look at the data in the papers listed below, none of them come close to showing these kinds of results. For the experiments involving cells grown in the lab, a proportion of the cells are killed or stop growing, but some of them carry on. Similarly in animal experiments, there is no data that shows a 100 per cent success rate for cannabinoids. For example, most mice treated with cannabinoids will still have tumours, although the cancers may be growing more slowly and spread less in some of them.
This isn’t just true for cannabinoids – it’s true for virtually all cancer drugs used today. Cancer is a very complex biological problem – there are hundreds of different types of cancer, each with important molecular and genetic differences. There’s good evidence to show that every individual’s cancer is as unique as they are, and that tumours can evolve and change within the body to become resistant to treatments.
We know that cancer drugs don’t work for everyone all the time – that’s why there’s so much effort going on to find more effective treatments – but it’s vital that doctors have a solid body of evidence showing how well the treatments they’re using are likely to work. If you or someone you loved were going to take any kind of drug, would you be happy if it had only been tested in very high doses on cancer cell lines grown in the lab, or in mice injected with cancer cells? Or would you want to know that it had been trialled in large numbers of people, and there was good data on how effective it is, whether it’s safe in the dose given, what the side effects are, and the proportion of people that can be expected to get better?
This kind of evidence can only come from a combination of lab studies leading to clinical trials. At the moment, while there are hundreds of interesting lab studies of cannabinoids (just some of which are included in the list below) there is only one clinical trial that has been published. So for now, cannabinoids, whether natural or synthetic, are a very long way from being what we would describe as a “cure” for any type of cancer.
We’ve looked at each of the papers in one of the commonly-seen lists (for example, here), and noted down the kinds of experiments they are. Many of them are available as open access papers, so it’s possible to look at the data for yourself. Hopefully this is a useful explanation of the kind of scientific research that is currently ongoing into cannabinoids and cancer, and the process of gathering evidence to show whether a potential cancer therapy works.
Cannabis, CBD oil and cancer
Cannabis is a plant and a class B drug. It affects people differently. It can make you feel relaxed and chilled but it can also make you feel sick, affect your memory and make you feel lethargic. CBD oil is a chemical found in cannabis.
- Cannabis has been used for centuries recreationally and as a medicine.
- It is illegal to possess or supply cannabis as it is a class B drug.
- Research is looking at the substances in cannabis to see if it might help treat cancer.
- There are anti sickness medicines that contain man-made substances of cannabis.
What are cannabis and cannabinoids?
Cannabis is a plant. It is known by many names including marijuana, weed, hemp, grass, pot, dope, ganja and hash.
The plant produces a resin that contains a number of substances or chemicals. These are called cannabinoids. Cannabinoids can have medicinal effects on the body.
The main cannabinoids are:
- Delta-9-tetrahydrocannabinol (THC)
- Cannabidiol (CBD)
THC is a psychoactive substance that can create a ‘high’ feeling. It can affect how your brain works, changing your mood and how you feel.
CBD is a cannabinoid that may relieve pain, lower inflammation and decrease anxiety without the psychoactive ‘high’ effect of THC.
Different types of cannabis have differing amounts of these and other chemicals in them. This means they can have different effects on the body.
Cannabis is a class B drug in the UK. This means that it is illegal to have it, sell it or buy it.
CBD oil, cannabis oil and hemp oil
There are different types of oil made from parts of the cannabis plant. Some are sold legally in health food stores as a food supplement. Other types of oil are illegal.
CBD oil comes from the flowers of the cannabis plant and does not contain the psychoactive substance THC. It can be sold in the UK as a food supplement but not as a medicine. There is no evidence to support its use as a medicine.
Cannabis oil comes from the flowers, leaves and stalks of the cannabis plant. Cannabis oil often contains high levels of the psychoactive ingredient THC. Cannabis oil is illegal in the UK.
Hemp oil comes from the seeds of a type of cannabis plant that doesn’t contain the main psychoactive ingredient THC. Hemp seed oil is used for various purposes including as a protein supplement for food, a wood varnish and an ingredient in soaps.
Why people with cancer use it
Cannabis has been used medicinally and recreationally for hundreds of years.
There has been a lot of interest into whether cannabinoids might be useful as a cancer treatment. The scientific research done so far has been laboratory research, with mixed results, so we do not know if cannabinoids can treat cancer in people.
Results have shown that different cannabinoids can:
- cause cell death
- block cell growth
- stop the development of blood vessels – needed for tumours to grow
- reduce inflammation
- reduce the ability of cancers to spread
Scientists also discovered that cannabinoids can:
- sometimes encourage cancer cells to grow
- cause damage to blood vessels
Cannabinoids have helped with sickness and pain in some people.
This means a cannabis based product used to relieve symptoms.
Some cannabis based products are available on prescription as medicinal cannabis. The following medicines are sometimes prescribed to help relieve symptoms.
Nabilone is a drug developed from cannabis. It is licensed for treating severe sickness from chemotherapy that is not controlled by other anti sickness drugs. It is a capsule that you swallow whole.
Sativex is a cannabis-based medicine. It is licensed in the UK for people with Multiple Sclerosis muscle spasticity that hasn’t improved with other treatments. Sativex is a liquid that you spray into your mouth.
Researchers are looking into Sativex as a treatment for cancer related symptoms and for certain types of cancer.
How you have it
Cannabis products can be smoked, vaporized, ingested (eating or drinking), absorbed through the skin (in a patch) or as a cream or spray.
CBD oil comes as a liquid or in capsules.
Prescription drugs such as Nabilone can cause side effects. This can include:
- increased heart rate
- blood pressure problems
- mood changes
- memory problems
Cannabis that contains high levels of THC can cause panic attacks, hallucinations and paranoia.
There are also many cannabis based products available online without a prescription. The quality of these products can vary. It is impossible to know what substances they might contain. They could potentially be harmful to your health and may be illegal.
Research into cannabinoids and cancer
We need more research to know if cannabis or the chemicals in it can treat cancer.
Clinical trials need to be done in large numbers where some patients have the drug and some don’t. Then you can compare how well the treatment works.
Many of the studies done so far have been small and in the laboratory. There have been a few studies involving people with cancer.
Sativex and temozolomide for a brain tumour (glioblastoma) that has come back
In 2021, scientists reported the final results of a phase 1 study to treat people with recurrent glioblastoma (a type of brain tumour that has come back). The study looked at Sativex in combination with the chemotherapy drug temozolomide.
Researchers found that adding Sativex caused side effects, which included, vomiting, dizziness, fatigue, nausea and headache but patients found the side effects manageable.
They also observed that 83 out of 100 people (83%) were alive after one year using Sativex, compared to 44 out of 100 people (44%) taking the placebo.
However, this phase 1 study only involved 27 patients, which was too small to learn about any potential benefits of Sativex. The study wanted to find out if Sativex and temozolomide was safe to take by patients.
Researchers have now started a larger phase 2 trial called ARISTOCRAT, to find out if this treatment is effective and who might benefit from it. Speak to your specialist if you want to take part in a clinical trial.
Sativex and cancer pain
There are trials looking at whether Sativex can help with cancer pain that has not responded to other painkillers.
The results of one trial showed that Sativex did not improve pain levels. You can read the results of the trial on our clinical trials website.
Cancer and nausea and vomiting
A cannabis based medicine, Nabilone, is a treatment for nausea and vomiting.
A Cochrane review in 2015 looked at all the research available looking into cannabis based medicine as a treatment for nausea and sickness in people having chemotherapy for cancer. It reported that many of the studies were too small or not well run to be able to say how well these medicines work. They say that they may be useful if all other medicines are not working.
A drug called dexanabinol which is a man made form of a chemical similar to that found in cannabis has been trialled in a phase 1 trial. This is an early trial that tries to work out whether or not the drug works in humans, what the correct dose is and what the side effects might be. The results are not available yet. You can read about the trial on our clinical trials database.
Word of caution
Cannabis is a class B drug and illegal in the UK.
There are internet scams where people offer to sell cannabis preparations to people with cancer. There is no knowing what the ingredients are in these products and they could harm your health.
Some of these scammers trick cancer patients into buying ‘cannabis oil’ which they then never receive.
You could talk with your cancer specialist about the possibility of joining a clinical trial. Trials can give access to new drugs in a safe and monitored environment.
The science blog on our website has more information about cannabis and cancer.