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.