UK investigating cannabinoids Effects on Cancer

UK investigating cannabinoids Effects on Cancer

The research

Note: Please consult a doctor for medical examination, and assistance, before taking any cannabis products like cannabinoids if you are suffering from 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.

How do researchers study cannabis?

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 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 of the effect of different cannabinoids.

Through many detailed experiments – summarized 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 they 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 their 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 of the majority of 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 the research. Providing early indications of the benefits of particular treatments, they don’t necessarily hold true for people.

glass lab bottles on a shelf

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 tumors, and 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 tumor – 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.

Cannabis in clinical trials

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 the glioblastoma multiforme brain tumors 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 of 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 trial results are yet to be published.

Groups exploring cannabinoids and cancer

  • Dr. Wai Liu at St George’s University 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.
  • Professor Susan Short is the lead on the ARISTOCRAT trial that is evaluating the combined use of Sativex and the chemotherapy drug temozolomide to treat people with recurrent glioblastoma.
  • The Medical Cannabis Research Group at Imperial College London is exploring cannabinoid use as it relates to potential therapies for inflammation and pain linked to cancer.
  • The charity DrugScience is 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 tumor 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 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 vaporized cannabis and cancer risk.

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 legalized 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 the 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 compared 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.

How does the endocannabinoid system fight cancer?

In recent years, the endocannabinoid system has received great interest as a potential therapeutic target in numerous pathological conditions. Cannabinoids have shown an anticancer potential by modulating several pathways involved in cell growth, differentiation, migration, and angiogenesis.

cannabinoids and brain tumors

Cannabis, cannabinoids, and cannabis derivatives

Cannabis is the dried preparation, or resinous extract, of the flowers or leaves of the cannabis plant, a member of the hemp family.

The parts of cannabis that are considered important for medical reasons are called cannabinoids. This is the name for the complex chemicals found in cannabis that are responsible for the effect cannabis has on the body. Two cannabinoids are of particular interest:

  • THC – delta-9 tetrahydrocannabinol (responsible for the psychoactive and addictive effects of cannabis)
  • CBD – cannabidiol

Cannabis derivatives is a general term for all products that are produced using different parts of the cannabis plant, including:

  • cannabis-based medicines that certain healthcare professionals can prescribe (for example, Sativex and Nabilone)
  • cannabis products that don’t contain THC, which can be sold legally in the UK as food supplements (for example CBD oil or hemp oil)
  • cannabis products that do contain THC, which are currently illegal in the UK (for example, street cannabis or cannabis oil).

It’s important that you understand the difference between cannabis products that contain CBD and cannabis products that don’t contain THC, as they can have different effects and are legally treated differently.

What is the evidence for cannabis-based products in the treatment of brain tumors?

Treating brain tumors

Currently, the evidence that cannabis-based products can treat brain tumors themselves is limited.

Preliminary studies from the lab suggest that cannabinoid chemicals THC and CBD can stop glioblastoma (GBM) cells from growing. Causing them to die and disrupting the blood supply to the tumor cells.

And, earlier this year, an early-stage trial was led by Professor Susan Short. Suggested that adding a specific blend of these chemicals – in the form of a drug called Sativex – to chemotherapy could potentially help treat recurrent GBMs more effectively.

Treating side-effects

There’s no conclusive evidence for the use of cannabis and its products, such as cannabis oil and CBD oil, for other therapeutic purposes, i.e. pain relief and treating chemotherapy-induced nausea and vomiting.

As such, the cannabis-based drug, Nabilone, has a medical license and can be legally prescribed for chemotherapy-induced nausea and vomiting.

For more information, see the government’s review.

Cannabis medicines have been used to help with nausea, however these are different to the products that have been tested for use to treat cancers.

Professor Susan Short, Consultant in Clinical Oncology

Is it safe to use cannabis-based products?

Any supplements, alternatives, or complementary treatments that you or your loved one wish to use could interact with other medications, such as anti-epileptic medicines, steroids, or chemotherapy. You should always discuss this with your medical team before deciding to use cannabis-based products.