Cannabidiol (CBD) oil might be safe and well tolerated but it’s ineffective for the relief of symptoms in cancer patients receiving palliative care, an Australian trial has shown.
Despite its increasing use in the community for a growing range of indications, researchers at the Mater Research Institute -University of Queensland have challenged the popular perception that CBD has a place in advanced cancer care.
“With current evidence, it is difficult to justify government subsidisation of the cost of CBD nor recommend that patients pay for CBD products,” they said.
The phase 2b RCT randomised 144 patients with advanced cancer and symptom distress to titrated CBD oil 100 mg/mL, 0.5 mL once daily to 2 mL three times a day, or matched placebo for 28 days. Standard palliative care was provided to all participants.
The study, published in the Journal of Clinical Oncology [link here], found the mean change in total symptom distress score (TSDS) from baseline to day 14 was –6.2 (SD, 14.5) for placebo and –3.0 (SD, 15.2) for CBD with no significant difference between arms (mean difference in change, –3.2 [95% CI, –8.5 to 2.1], P = .24).
As well, all components of the Edmonton Symptom Assessment Scale (ESAS) improved over time for both groups.
“There was no detected difference between arms in TSDS change from baseline in physical, emotional, or well-being subsets at day 14 or 28 nor in any of the individual ESAS components including pain, anxiety, depression, nausea, and appetite scores or tumour type,” it said.
The study said the median daily CBD dose was 400 mg.
Interestingly, most participants in both arms reported feeling better or much better on the Patient Global Impression of Change at day 14 (53% on CBD v 65% on placebo) and day 28 (70% v 64%), despite no objective improvement in ESAS score.
Mean total Depression Anxiety Stress Scale (DASS) scores fell slightly over time from baseline to days 14 and 28 in both arms.
“There was no detectable effect of CBD on change in physical or emotional functioning, overall quality of life, fatigue, nausea and vomiting, pain, dyspnea, or appetite loss from baseline to day 28 with minor improvement over time in both groups.”
The study found adverse events were common throughout the study but there were no significant differences between treatment groups except for new or worse dyspnea which was more common in the CBD group (8 v 2 participants, p=0.04).
“There was no suggestion of deleterious drug interactions in participants,” the study said.
“Despite widespread public belief in the benefits of cannabis, this study failed to demonstrate an improvement in symptom control from CBD oil in patients with advanced cancer over that obtained from palliative care alone.”
“Moreover, previous research has failed to demonstrate a meaningful beneficial effect on individual symptoms, for example, in pain and appetite.”
The investigators included Professor Janet Hardy, Director of Palliative and Supportive Care across the Mater Group, and Professor Phillip Good, Director of St Vincent’s Hospital Palliative Care Unit in Brisbane.
They noted that a major criticism of the study was likely to be the use of pure CBD oil.
However, in contrast to delta-9-tetrahydrocannabinol (THC), CBD had no psychoactive effects and does not impair driving ability.
“Many believe that THC contributes more to symptom control and that the combination of CBD/THC products is more beneficial.”
They said ongoing studies would consider the contribution of THC to symptom management and may also consider using “some form of happiness scale” as an outcome measure, given many patients report a nonspecific improvement in overall well-being.
The study said 36% of patients elected to purchase a medicinal cannabis product after the trial – despite the lack of objective evidence of benefit even when they believed they had been on the active arm.