Cannabis in Palliative Care: A Systematic Review of Current Evidence.

Context: Palliative care aims to improve the quality of life in patients with incurable illness. Medicinal cannabis (MC) has been used in the palliative care setting to address multiple symptoms in patients.

Objectives: To evaluate the full scope of available literature investigating the effects and potential harms of MC on symptom management and quality of life in palliative care.

Methods: PubMed, Embase, The Cochrane Library and clinicaltrials.gov were searched for eligible articles, published between 1960 and September 9, 2021. Quality of the evidence was assessed in accordance with Grading of Recommendations, Assessment, Development and Evaluations. Risk of bias was assessed using the RoB 2 tool for randomised controlled trials and the Risk of Bias in Non-randomized Studies-of Interventions (ROBINS-I) tool for non-randomized trials.

Results: Fifty-two studies (20 randomised; 32 non-randomised) with 4786 participants diagnosed with cancer (n = 4491), dementia (n = 43), AIDS (n = 235), spasticity (n = 16), NORSE syndrome (n = 1) were included. The quality of evidence was 'very low' or 'low' for all studies, and low for only two randomised controlled trials. Positive treatment effects (statistical significance with P < 0.05) were seen for some MC products in pain, nausea and vomiting, appetite, sleep, fatigue, chemosensory perception and paraneoplastic night sweats in patients with cancer, appetite and agitation in patients with dementia and appetite, nausea and vomiting in patients with AIDS. Meta-analysis was unable to be performed due to the wide range of cannabis products used and the heterogeneity of the study outcomes.

Conclusion: While positive treatment effects have been reported for some MC products in the palliative care setting, further high quality evidence is needed to support recommendations for its use in clinical practice.