Cannabidiol (CBD) oil failed to improve cancer-related symptoms beyond the benefits of palliative care, a randomized phase II trial showed.
The change in a standard symptom scale was actually greater with the addition of placebo to palliative care: -6.2 points versus -3.0 points with CBD oil. The proportion of patients who met criteria for response also favored the placebo group, and the change in scores for individual symptoms did not differ between the placebo and CBD oil groups, Janet Hardy, MD, of the University of Queensland in Brisbane, Australia, and colleagues reported in the Journal of Clinical Oncology.
„This study has significant implications for policymakers regarding both approved indications for MC [medical cannabis] and its safe use,” the authors wrote. „Medical cannabis has been approved in several countries for palliative care in the belief that it might improve the QoL [quality of life] of patients with advanced disease.
„CBD is a popular cannabis product in the community as it has no psychoactive effects and does not impair driving ability,” the team added. „With current evidence, it is difficult to justify government subsidization of the cost of CBD nor recommend that patients pay for CBD products.”
The results are not surprising, said Marcin Chwistek, MD, a supportive care and palliative medicine specialist at Fox Chase Cancer Center in Philadelphia, who was not involved with the study.
„The results are consistent with what I have observed in our clinical practice,” he told MedPage Today via email. „CBD oil alone is widely available and used by many cancer patients. However, very few patients seem to benefit from it. It is important to note that patients were also receiving standard palliative care that focuses on the management of cancer-related symptoms and already utilizes many effective therapies. Therefore, it may be difficult to observe a meaningful change in patients’ symptoms with a short term addition of CBD oil.”
Using a different cannabis product might have made a difference, such as a 1:1 combination of THC and CBD, Chwistek continued. Limited evidence suggests that combination is helpful for cancer-related pain.
The oncology community has mixed feelings about use of medicinal CBD. Despite a lack of evidence, the products are usually well tolerated, so many oncologists do not discourage the products’ use, particularly when patients express an interest.
„What is also needed is evidence related to the potential effect of MC [medical cannabis] on the growth of cancer cells or effects of anticancer therapy,” said Chwistek. „At this time, we do not know if MC interferes with anticancer therapy in any meaningful way.”
The trial did provide some needed evidence regarding use of CBD products in patients with advanced cancer, said Kimberson Tanco, MD, of the University of Texas MD Anderson Cancer Center in Houston. Most published systematic reviews have shown limited supporting evidence. Controlled clinical trials with more patients followed for longer duration are needed to assess CBD products’ benefits and toxicities, but such studies have been challenging to conduct.
„Personally, as an actively practicing clinician, the majority of reports of symptom-related benefits that I have heard have also been anecdotal from patients’ or caregivers’ accounts,” said Tanco.
He also has sensed mixed feelings among oncology practitioners toward use of CBD to manage cancer symptoms.
„Clinicians are asked more and more by patients and their caregivers regarding the potential role and use of these products while reporting limited knowledge of these products,” said Tanco.
The Australian study involved 144 patients with advanced cancer and symptom distress, as reflected by an Edmonton Symptom Assessment Scale (ESAS) total score ≥10/90. All patients received standard professionally administered supportive/palliative care and were randomly assigned to CBD oil or placebo for 28 days. The primary outcome was change in ESAS total score at day 14, and response was defined as a decrease in ESAS total score ≥6 on day 14.
The results showed no statistically significant difference in ESAS total score at day 14, although the numerical comparison favored the placebo group. In the placebo group, 58.7% of patients met criteria for response as compared with 44.8% in the CBD oil group, which was also not significantly different. Individual components of the ESAS declined in both groups with no significant differences between groups. The titrated dose of CBD oil did not have any significant associations with opioid dose.
„There was no detectable effect of CBD on quality of life, depression, or anxiety,” the authors said of the results. „Adverse events did not differ significantly between arms apart from dyspnea that was more common with CBD. Most participants [in both groups] reported feeling better or much better at days 14 … and 28.”
The study was supported by the Commonwealth of Australia Medical Research Future Fund.
Hardy disclosed a relationship with GD Pharma.
Chwistek and Tanco reported no relevant relationships.