Mr Jamie Murphy, Imperial College LondonOne of the questions my patients most frequently ask me is if it is okay to take cannabis based supplements to help treat their cancer? Often patients have read a lot about these supplements.

In particular, patients who have not had a great deal of benefit from conventional treatment are interested in these supplements as they may have come across other people’s descriptions of dramatic health improvements.

Some patients have even reported that they have been ‘cured’ by cannabis supplements. However, it is impossible to tell what impact these supplements have really had, as there is usually no medical information included in these extraordinary reports, such as the other cancer treatments the patient was receiving or the stage of their disease.

Therefore, while there is a lot of information on the Internet about cannabis supplements it is important only to trust reliable sources (such as Macmillan and Cancer Research UK) and appreciate that stories you have read from individuals are not medical studies.

Before discussing what evidence research studies have shown it is important to highlight that not all cannabis based supplements are legal in the UK. There are two main substances that have been identified from cannabis. The first is tetrahydrocannabidiol, also known as THC. It is illegal to use this in the UK, as it is a Class B drug. The second substance is cannabidiol, also known as CBD, which is legal and often comes in the form of an oil.

So what evidence is there that any of the available cannabis based supplements may help treat cancer? There have been hundreds of studies assessing both THC and CBD based supplements and therefore it is important to try and summarise these to give the overall picture. To cut to the chase, at the present time there simply isn’t enough reliable evidence to show that any of the cannabis based supplements, natural or manmade, help treat cancer. In particular, there is no reliable evidence that ‘street’ or ‘home-grown’ cannabis has an anti-cancer effect. There is also no evidence to support any cannabis-based supplements preventing cancer. However, the work in these fields is ongoing.

There is good evidence that cannabis based supplements may be of benefit in managing pain from cancer or side effects from treatment. But there are now safer and more effective treatments available to manage these symptoms and doctors only use cannabis-based medications where other approaches fail.

I often hear patients express the opinion that the drug companies are either not studying cannabis as a cancer treatment or suppressing the evidence, because they cannot patent these substances and wouldn’t make any money from them. It is extremely important to highlight that this isn’t true. It is also important to say that I am someone who has no relationship, financial or otherwise, with any drug company. These companies would be able to patent modifications to cannabis supplements made in the laboratory if these changes made them more effective, or they developed changes that made more effective ways for cannabis-based medications to be given to patients. It is also important to stress the only way potential benefits from cannabis based supplements could be reliably demonstrated would be for drug company purity grade cannabis-based medications to be studied in large high quality research trials. As I said before studies like these are ongoing.

If you chose to take cannabis-based supplements despite the lack of evidence I have outlined above it is very important you inform your oncologist before you do. This is so they know all the medications and supplements you are taking to make sure they don’t interact. Even if these supplements are sold to you legally there are other factors that you need to consider before purchasing them. Buying them across the Internet is not without risk, as you can’t be truly certain of what you are buying. It is impossible to be certain of how pure the supplement is or if contains THC, which in addition to being illegal may cause side effects such as paranoia or hallucinations, or interact with your other medications. In addition, there are Internet scams where people offer to sell these supplements but after payment the supplements aren’t sent to the patient.

Finally, it is important to appreciate that if you choose to take supplements like those I have described above that you should not reject the conventional cancer treatments you are offered in favour of unproven alternatives. Always be guided by your oncologist as making the decision to reject chemotherapy in favour of unproven supplements, whatever they are, may significantly shorten your life or mean you miss out on effective symptom control.

Consultant Surgeon – Peritoneal (HIPEC/PIPAC) & Pelvic Oncology
Imperial College, London

*This article originally appeared on LinkedIn, accessed May 5th 2020, and is reproduced here with the full permission of the author.