Cannabidiol (CBD) oil did not improve symptom distress more than a placebo for people with advanced cancer who were receiving palliative care, according to findings published in the Journal of Clinical Oncology.

People with cancer are increasingly using cannabis and its components, including cannabidiol, as it becomes legal in more states. Some people prefer CBD over whole cannabis because it does not have psychoactive effects. While some studies have found that cannabis reduces cancer-related pain, research remains limited.

Janet Hardy, MD, of the University of Queensland in Australia, and colleagues conducted a Phase II trial to assess whether CBD oil would help people receiving palliative care for advanced cancer to better tolerate their symptoms.

The study included 144 adults with advanced cancer who were experiencing symptom distress, which was assessed using a questionnaire called the Edmonton Symptom Assessment System (ESAS). The assessment takes into account the intensity of nine common symptoms: pain, tiredness, drowsiness, nausea, appetite, depression, anxiety, shortness of breath and overall well-being. People with an ESAS score of at least 10 out of a maximum score of 90 were included.

The participants were randomly assigned to two groups. One group received CBD oil with a strength of 100 milligrams per milliliter, at doses ranging from 0.5 ml once a day to 2.0 ml three times daily for 28 days. Those in the control group received placebo oil for the same duration. All participants also received specialized palliative care.

The main outcome of the study was the ESAS total symptom distress score after two weeks of treatment. The researchers set the criteria for a response as a decrease of at least 6 points on day 14. Out of the 144 participants, 58 people in the CBD group and 63 in the placebo group reached this time point.

More people in the placebo group (59%) met the criteria for response than those in the CBD group (45%). From baseline to day 14, the total symptom distress score decreased by 6.2 points in the placebo group and by 3.0 points in the CBD group. Neither difference was statistically significant. There was also no difference in the need for opioids.

All components of the symptom assessment improved over time in both groups. Participants felt better or much better on day 14 (53% on CBD and 65% on placebo) and day 28 (70% on CBD and 64% on placebo), with no significant differences between the groups. CBD had no notable impact on depression, anxiety or quality of life. Adverse events were generally similar, but more people in the CBD group reported shortness of breath.

“CBD oil did not add value to the reduction in symptom distress provided by specialist palliative care alone,” wrote the study authors.

While larger controlled trials are needed to better establish the pros and cons of CBD products for people with advanced cancer, the results of this study suggest that the benefits do not justify the costs, according to the researchers.

Click here to read the study abstract in the Journal of Clinical Oncology.

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