Initial results from a series of medicinal cannabis clinical trials have found that CBD oil performed no better than a placebo in reducing symptom burden among palliative care patients living with advanced cancer.
The randomised, blinded, placebo-controlled trial was carried out by Mater Research and the University of Queensland, examining how CBD affected symptom relief across 144 patients from the greater Brisbane area.
The study was among the first to receive funding from the Medical Research Future Fund (MRFF) in 2018, with the goal of addressing the shortage of scientific evidence around medicinal cannabis for pain relief and symptom distress. Results have been published in the Journal of Clinical Oncology.
Participants were either given a self-selected dose of CBD of up to 600mg per day or assigned to the placebo group. Everyone enrolled in the trial continued to receive standard palliative care throughout.
Professor Janet Hardy, the trial's research lead and Mater director of palliative and supportive care, said: "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.
"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."
Even without evidence of clinical benefit from CBD oil, more than one third (36%) of trial participants chose to buy a medicinal cannabis product after the study concluded — despite not knowing whether they had been receiving CBD or the placebo.
"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," Professor Hardy said.
A second trial, anticipated to be published in mid-2023, will examine the effects of THC used alongside CBD, while a third will test a different combination of the two cannabinoids.
