CBD Oil Does Not Improve Quality of Life for Palliative Care Cancer Patients, Study Finds

CBD oils do not improve patients’ ratings of pain, depression, anxiety, or quality of life, a new trial of palliative care patients with advanced cancer has found.

Published in the Journal of Clinical Oncology, researchers from Mater Research and the University of Queensland gave a group of 144 advanced cancer patients either a placebo or a pure CBD extract to take alongside their usual palliative care. Based on total symptom distress scores reported by both groups, the researchers concluded that there was no significant difference in effects between the placebo and the CBD oil.

However, despite the lack of detectable improvement in their symptoms, many participants reported generally feeling “better” or “much better” by the end of the study. Whether this was a result of a placebo effect or of an improvement in another domain unmeasured, such as sleep quality, is still unclear, the researchers said.

CBD does not provide significant relief

This randomized, blinded, placebo-controlled trial enrolled 144 patients with advanced cancer receiving palliative care in the greater Brisbane area. Patients were randomized to be given either a placebo or a CBD oil, which was titrated up to a dose preferred by each individual patient at the start of the experiment.

Using in-person and telephone assessments, the trial participants completed a range of questionnaires designed to assess their total symptom burden, changes in other medication use, anxiety and depression levels, and overall quality of life. Participants were also asked to report any adverse effects experienced following the commencement of the trial.

Examining this data, the researchers found that CBD did not significantly improve quality of life, depression, or anxiety. CBD was also no better than the placebo at reducing the total symptoms distress scores (TSDS) reported by patients.

“The trial found there was no detectable effect of CBD on change in physical or emotional functioning, overall quality of life, fatigue, nausea and vomiting, pain, dyspnoea or appetite loss,” Professor Janet Hardy, study author and the director of Palliative and Supportive Care at Mater, said in a statement. “There was no demonstration of an improvement in symptom control from CBD oil in patients with advanced cancer over that obtained from palliative care alone.”

“It did find however that CBD was safe and well tolerated with minimal adverse effects experienced due to CBD during the trial period.”

The prevalence of adverse events was comparable between the CBD and placebo groups, with the CBD group being only slightly more likely to report labored breathing. Any serious adverse events recorded by participants were determined by the researchers to be unrelated to the clinical trial.

Medical cannabis in Australia

This CBD oil trial was one of the first to be awarded funding from the Medical Research Future Fund (MRFF), a $20 billion long-term investment fund operated by the Australian Government to support research and innovation in healthcare. The researchers behind the trial say that these types of studies will help to fill in the current knowledge gaps surrounding medical cannabis usage.

“The best way to describe the uptake of medicinal cannabis following its legalization was as a social phenomenon – everyone wanted it, but there was little evidence to guide its usage,” Hardy said.

“Usually, new products entering the market have gone through extensive pre-clinical studies regarding best dosage and usage, however medicinal cannabis entered the market with very little guidance.”

The only cannabis-based medicines currently registered on the Australian Register of Therapeutic Goods are Epidiolex, an oral CBD spray intended to treat rare types of epilepsy, and Sativex, a mixed CBD and THC oromucosal spray to relieve spasticity in people with multiple sclerosis (MS). However, other CBD oils and other unregistered medical cannabis products can be accessed via a doctor or specialist issuing a prescription or taking part in a clinical trial.

“Despite very limited evidence of benefit and no clear guidance around which cannabinoid or combination to use for which indication and at what dose, the use of cannabis for therapeutic benefit has risen exponentially over the past few years with strong public belief in its benefit,” Hardy said.

What about other medical cannabis products that aren’t CBD?

In their paper, the Mater Research and University of Queensland researchers do acknowledge one flaw of their work, that it only focused on pure CBD oils. As seen in other reports, cancer patients in other jurisdictions with different medical cannabis access laws do tend to self-select for cannabis products with a higher THC content.

“The next stage of the trial should determine whether THC, despite having psychoactive effects, is of greater benefit for patients in palliative care,” Hardy said. “We are aiming to have the findings of our second trial ready to publish in mid-2023.”

The researchers are also planning to conduct a third study looking at products containing a mix of CBD and THC, Hardy revealed.

Interestingly, despite the CBD oil in this trial apparently producing no significant effect on the patients’ total symptom burden, around one-third of trial participants subsequently chose to buy some kind of medical cannabis product once the trial had concluded. The researchers did not elaborate on whether this referred to CBD oils alone or a greater variety of possible medical cannabis products.

“Despite the lack of evidence of benefit, more than one third (36%) of participants in the first study elected to purchase a medicinal cannabis product after the trial, despite being unaware if they were taking the CBD or placebo,” Hardy said.

“Many participants reported a non-specific improvement in overall well-being, which has led us to consider some form of “happiness” scale in future studies,” she added.

Research into the effectiveness of different medical cannabis products for use in palliative care treatments is ongoing. While individual studies have reported promising results, a recent review published in the Journal of Pain and Symptom Management found significant issues with quality and bias in many current studies.

“In conclusion, despite a range of positive treatment effects reported in the included studies, the quality of the evidence assessed does not support recommendations for the use of medicinal cannabis in the palliative care setting,” the review authors wrote.