UMCG starts scientific research into cannabis oil and liver-cancer

The University Medical Center Groningen (UMCG) will start this year, 2021, a study on the effect of cannabis oil on liver-cancer patients who have exhausted all the avenues of treatment. The purpose of the pilot study, which will have 20 participants, is to see whether cannabis oil can reduce liver-cancer tumours. This is unique, as this type of study has not been carried out before. “It is pioneering in many ways”, said surgeon and lead researcher Maarten Nijkamp.

In three years from now, Nijkamp and his colleague Frederik Hoogwater, oncologist Derk Jan de Groot and gastroenterologist Frans van der Heide would like to be able to say whether medicinal cannabis oil has an impact on the growth, or rather the regression, of liver-cancer tumours. In this study twenty patients will be enrolled who all have come to the end of their standard treatment but still have a good liver function. The latter is important, because a functioning liver will ‘process’ cannabis oil on the basis of natural processes. As soon as the correct dose of cannabis oil has been determined and administration has started, a liver scan will be performed for every participant after three, six and nine months. Blood samples will also be taken to study the liver function and to check the presence of tumour markers. No later than in 2024 – or as much sooner as possible – the research team aims to present a clear conclusion.

UMCG starts scientific research into cannabis oil and liver-cancer

Anecdotal evidence

The idea for this clinical trial came up more than three years ago, when an UMCG patient with advanced liver cancer showed remarkable results upon using cannabis oil. The tumours in his liver started to disappear gradually after he started taking cannabis oil and now – five years following the diagnosis – he has been given the ‘all clear’. When comparable results were seen in a second patient, Nijkamp and his colleagues started to become excited. “We would have been equally excited if the patients had used fish oil”, tempers Nijkamp.

“However, cannabis and cannabis products are unusual. You only need to go on the internet to find a fair amount of anecdotal evidence for cannabinoids as a weapon in the fight against cancer. However, it is incidental and you do not know in how many patients the use of cannabinoid-based products did not have the desired effects. Then there is laboratory research that demonstrates that cannabis can have an inhibiting effect on the growth of liver-cancer cells. However, if you pour hot water or chlorine on cancer cells in a laboratory, you will see a comparable effect. In other words, you cannot state that cannabinoid-based medicines are able to cure cancer – in this case liver cancer – because there is no scientific proof. That requires a clinical trial with real patients. These two patients gave the topic ‘cannabis oil and liver cancer’ ‘meaning’ for my colleagues and me, because we are scientists as well as specialists. From a scientific point of view, we felt compelled to start up a trial. At the same time, we knew that it would be pioneering in many respects.”


The set-up up of the trial presented a number of practical issues for Nijkamp and his team. First of all, the trial topic had to be approved and reviewed by various bodies, including the Medical Research Ethics Committee. Nijkamp: “Cannabis oil is not a registered drug and there are many unknowns. The wildest stories do the rounds, and we certainly did not want to fuel any fires with this trial. The review committee made sure that our trial complies with all the requirements imposed on such scientific research. At the same time, we needed answers to a number of questions. Such as: What are the substances that make cannabis effective? In what ratio are they required in the oil? Which dose is most suitable? Both patients used cannabis oil that contained THC and CBD, so that was our starting point.”

Good foundations

Then the team had to look for a manufacturer and supplier of the oil. “It is not difficult to obtain cannabis oil, but medicinal cannabis oil is a different story. For a trial like this one, the bar has been raised as high as possible”, said Nijkamp. “It goes without saying that the review bodies do the same. You need to have solid foundations: you need to procure material from a party with the right certificates for the production of your trial material. That is part of the requirements imposed on such a trial. You need to be sure that the trial material has a consistent composition, because otherwise you cannot make any statements about the results of the study. We knew that since a few years the Transvaal Pharmacy specialised in the responsible production of medicinal cannabis oil. They prepare that on the basis of standardised medicinal cannabis that is produced by Bedrocan under a contract with the Ministry of Health. The oil of Transvaal Apotheek is of a consistent quality and is tested by an independent laboratory. We knew that Transvaal Apotheek was working on obtaining certificates for the production of trial materials. That requires a significant amount of prior testing and review, and we had to wait for that to be completed. Then it was a case of selecting the right cannabis oil for the trial.”

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For this pilot study, a medicinal cannabis oil that was already part of the range of Transvaal Apotheek has been chosen. Nijkamp: “We used the composition of the oils that were used by both patients as the starting point. That was oil with a relative high THC content. Transvaal Apotheek makes the oil on the basis of the standardised plant varieties Bedrocan® and Bedrolite®; it contains 10 percent THC and 5 percent CBD and is known as ‘Transvamix®’. We will use that oil as the material for the clinical trial.”


The dosage was another point of attention, because in that sense cannabis oil is not comparable to regular medication. According to Nijkamp it may well be a reason why there have been very few clinical trials with cannabis or cannabis oil thus far. “Again, we were pioneering. With regular medication – like painkillers for example – there is a set dose; you know what the medication will do at a certain dose”, says Nijkamp. “Cannabis or cannabis oil is another story. Every patient responds differently to the product and the amount of oil that is required to be effective, may differ from patient to patient. That makes a trial much more complicated. For every patient we will raise the dose on a daily basis until there are side effects. Then we go down to the dose without side effects. In theory that would give you the highest possible dose without side effects.”

Pilot study

As far as we know, the UMCG is the first research institute in the world to carry out a study of cannabis oil for liver cancer. “In this form anyway”, said Nijkamp. “There are various laboratory studies into the effect of cannabis on tumours. We know about studies about cannabis oil for brain tumours, but as far as we know there has been no follow up. It goes without saying that cannabis is also used by cancer patients for a positive effect on the quality of life during treatment. So, this is a real pilot study. The study will only tell something about the effect of cannabis on patients with liver cancer who still have a functional liver. As soon as we know that it works in one patient, we will have taken one step forward and we can start thinking seriously about further research. Patients with liver cancer and liver damage, for example and other types of cancer. We might be able to observe that cannabinoids – in this ratio and for these patients – make a positive contribution to the quality of life. On that basis, cannabis-based products could play a set role in oncology in the future.
The outcome could also be that there is no response in any of the twenty people. Then, to that point, we have done what was required from a medical-scientific point of view, but would still be faced with a mystery in terms of why both patients were cured.”

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