MD, PhD, FMedSci, FRSB, FRCP, FRCPEd.

I was asked by the ‘Science Media Centre’ (SMC) to provide a short comment on the following press release (which was embargoed until today):

Daily use of cannabidiol (‘CBD’) oil may be linked to lung cancer regression 

… The report authors describe the case of a woman in her 80s, diagnosed with non-small cell lung cancer. She also had mild chronic obstructive pulmonary disease (COPD), osteoarthritis, and high blood pressure, for which she was taking various drugs.

She was a smoker, getting through around a pack plus of cigarettes every week (68 packs/year).

Her tumour was 41 mm in size at diagnosis, with no evidence of local or further spread, so was suitable for conventional treatment of surgery, chemotherapy, and radiotherapy. But the woman refused treatment, so was placed under ‘watch and wait’ monitoring, which included regular CT scans every 3-6 months.

These showed that the tumour was progressively shrinking, reducing in size from 41 mm in June 2018 to 10 mm by February 2021, equal to an overall 76% reduction in maximum diameter, averaging 2.4% a month, say the report authors.

When contacted in 2019 to discuss her progress, the woman revealed that she had been taking CBD oil as an alternative self-treatment for her lung cancer since August 2018, shortly after her original diagnosis.

She had done so on the advice of a relative, after witnessing her husband struggle with the side effects of radiotherapy. She said she consistently took 0.5 ml of the oil, usually three times a day, but sometimes twice.

The supplier had advised that the main active ingredients were Δ9-­tetrahydrocannabinol (THC) at 19.5%, cannabidiol at around 20%, and tetrahydrocannabinolic acid (THCA) at around 24%.

The supplier also advised that hot food or drinks should be avoided when taking the oil as she might otherwise feel stoned. The woman said she had reduced appetite since taking the oil but had no other obvious ‘side effects’. There were no other changes to her prescribed meds, diet, or lifestyle. And she continued to smoke throughout.

This is just one case report, with only one other similar case reported, caution the authors. And it’s not clear which of the CBD oil ingredients might have been helpful.

“We are unable to confirm the full ingredients of the CBD oil that the patient was taking or to provide information on which of the ingredient(s) may be contributing to the observed tumour regression,” they point out.

And they emphasise: “Although there appears to be a relationship between the intake of CBD oil and the observed tumour regression, we are unable to conclusively confirm that the tumour regression is due to the patient taking CBD oil.”

Cannabis has a long ‘medicinal’ history in modern medicine, having been first introduced in 1842 for its analgesic, sedative, anti-inflammatory, antispasmodic and anticonvulsant effects. And it is widely believed that cannabinoids can help people with chronic pain, anxiety and sleep disorders; cannabinoids are also used in palliative care, the authors add.

“More research is needed to identify the actual mechanism of action, administration pathways, safe dosages, its effects on different types of cancer and any potential adverse side effects when using cannabinoids,” they conclude.

The SMC published three invited comments:

Prof David Nutt, The Edmond J Safra Chair in Neuropsychopharmacology, Imperial College London, said: 

“This is one of many such promising single case reports of medical cannabis self-treatment for various cancers.  Such case reports are biologically credible given the adaptogenic nature of the endocannabinoid system.  A case report itself is not sufficient to give any form of proof that one thing caused the other – we need trials for that.  There are some controlled trials already started and more are required to properly explore the potential of medical cannabis in a range of cancers.”

Prof Edzard Ernst, Emeritus Professor of Complementary Medicine, University of Exeter, said: 

“Cannabinoids have been shown to reduce the size of prostate cancer tumours in animal models.  Previous case reports have yielded encouraging findings also in human cancers.  However, case reports cannot be considered to be reliable evidence, and there are currently no data from rigorous clinical trials to suggest that cannabis products will alter the natural history of any cancer.” 

Dr Tom Freeman, Senior Lecturer and Director of the Addiction and Mental Health Group, University of Bath, said: 

“These results are exciting and very encouraging for this patient.  However as a single case study the quality of scientific evidence is low and should not be used to change clinical practice.  People with lung cancer should always seek guidance from a healthcare professional when deciding on an appropriate treatment. 

“The product used by this patient reportedly contained high levels of THC (the intoxicating component of cannabis), and was sourced from outside the UK.  This type of product is very different to most CBD oils which predominantly contain CBD.  Unlike prescribed medicines, CBD wellness products lack assurance of quality, safety or efficacy and should not be used for medicinal purposes.”

The original paper has now been published and can be found here.

5 Responses to Does cannabidiol (‘CBD’) oil induce lung cancer regression?

  • Where are all the case reports from hemp-oil treated comparable malignancies that did not regress so happily?
    Would this report have been written and published if the lady had not had the good luck to survive her biopsy diagnosed non-small cell non-metastasised, non-advanced tumour? This report only proves that some histologically malignant tumours regress spontaneously. This is well known with different suspected and confirmed malignancies, especially in elderly who tend to produce relatively less agressive neoplasias. Another possibility is that the pathologist overdiagnosed the biopsy and this was simply an inflamatory lesion with malignant looking cells. Remember this was only a needle biopsy, not a tissue sample.

    • good point!

    • Remember this was only a needle biopsy, not a tissue sample.

      There is nothing in the paper to say that this was a needle biopsy. There were ultrasound-guided transbronchial needle biopsies of two mediastinal lymph nodes, performed together as a staging proceedure and which were negative. However, the diagnosis was made on the basis of a percutaneous CT-guided biopsy, and these usually involve taking a core of tissue. The authors also state that the case was reviewed by the multidisciplinary team, which in the UK involves review of the pathology by a specialist pathologist (all the authors are from hospitals with which I am familiar and in one of which I have previously worked), so I am inclined to believe the diagnosis.

      Where are all the case reports from hemp-oil treated comparable malignancies that did not regress so happily?
      Would this report have been written and published if the lady had not had the good luck to survive

      The answer is of course not. This case report was written up and published because it was unusual, and therefore subject to selection bias.

      This report only proves that some histologically malignant tumours regress spontaneously.

      Quite correct. The survival from diagnosis of all tumour types ranges from practically zero to many years; the life expectancy should properly be called the median survival, i.e. the point at which half of similar cases have died; the other half are still alive and some will go on to live for many years, even without treatment, before dying of something else. This is useful in trials for comparing different treatment but much less so in predicting how an individual will fare.

      Towards one extreme of this range are the spontaneous remissions, which are something that every oncologist sees from time to time. Some tumours continue to regress, and others shrink for a while before starting to grow again. There is a lot of interest in what mechanisms are responsible, and whether they reflect the biology of that particular tumour or peculiarities of the individual patient.

      I note from reading the paper (published in the BMJ and therefore not behind a paywall) that the original lesion was first seen in a chest radiograph in June 2018 having not been visible in February of the same year. A CT scan, also in June, showed a 41 mm lesion, suggesting that it was quite fast-growing. At the end of the staging investigations (carried out to determine the extent of spread and therefore the appropriate course of treatment) she had a second CT scan, which was in September 2018, and the lesion had by then reduced in size to 33mm, instead of continuing to grow at the original rate. However, two additional nodules had appeared elsewhere in the lungs; they were only 4mm and 6mm, and therefore non-specific, though with a fast-growing non small-cell lung cancer it would be quite common to see metastases with this appearance and time course. I note that they were not visible in subsequent scans, however.

      The authors suggest that the regression of the tumour could have been due to the cannabis oil preparation that she was taking, but she didn’t start this until August 2018, which was two months after the first scan and only one month before the second. Subsequent scans show a progressive slow reduction in size, with the lesion more-or-less gone after 30 months. Assuming a relatively fast exponential growth and a rather slower exponential shrinkage the findings are more in keeping with the regression starting at around the time of the biopsy. I would be tempted to wonder whether the biopsy triggered some sort of immunological response, but of course that is just a hypothesis.

      The authors state:

      The patient was referred to the cardiothoracic surgeons for consideration of a lobectomy, but surgery was declined by the patient following discussions with the surgeons.

      The patient was offered stereotactic ablative radiotherapy, but she declined this treatment as well.

      Existing cancer treatments could have severe side effects, both physically and mentally. This is why our patient decided on non-conventional self-treatment.

      I note that none of the three authors are oncologists, and indeed two of them are radiologists. They are clearly unfamiliar with the side-effects of radiotherapy for lung cancer or they would know that stereotactic ablative therapy is very well-tolerated. Major thoracic surgery in an 80-year-old is an entirely different matter and I would not be surprised if the surgeon himself advised against it.

      Anyway, this is an interesting case report, and given the widespread notion that cannabis oil might be effective treatment for malignancy it is something that should be investigated in a proper clinical trial. However, in the absence of evidence I would advise against its use as an antitumour agent in any other setting.

  • Quick comparison with Sativex treatment for MS where “feeling high” is the most common ADR and reason for quitting the therapy – maximum dosage 1.2 ml with about 6-7% of THC and CBD…
    So a statement that 1-1.5 ml of an oil containing 19-20% THC and CBD is to me rather questionable.

    • Another thing that makes me wonder about the contents of that oil is that the “woman said she had reduced appetite since taking the oil…”
      The reverse is a well-known effect of cannabis, either eaten or smoked. The famous “munchies.” Indeed, Roger Adams, who about 1940 determined the structures of several of the compounds in cannabis and synthesized them, developed an analogue that was supposed to be marketed to increase appetite. Whether it actually reached the market, I don’t know.
      The woman in the report was sick, and she was taking other drugs.

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