Cannabis-based medicinal products for cancer pain: a two-year prospective analysis from the UK medical cannabis registry

Context Cancer pain affects approximately 50% of patients with cancer, significantly reducing quality of life. Opioids remain first line for treatment however many patients report inadequate pain relief or intolerable side effects. Recently cannabis-based medicinal products (CBMPs) have become increasingly promising but are marred by low-quality evidence.Objectives To evaluate the effectiveness and safety of CBMPs in treating cancer pain using data from the UK Medical Cannabis Registry.Methods 116 patients were followed in a prospective observational study. Patient-reported outcome measures (PROMs), comprising of pain-specific and general measures of health-related quality of life, were collected at baseline, 1, 3, 6, 12, 18 and 24 month intervals. Adverse events were graded using the Common Terminology Criteria for Adverse Events. Longitudinal changes were evaluated using repeated-measures analysis of variance with Bonferroni-corrected post-hoc pairwise comparisons.Results improvements were observed across all PROMs (p < 0.050). At 24 months, clinically meaningful improvements (MCID) were achieved by 50.00% (n = 58), 47.41% (n = 5), and 54.31% (n = 63) of patients for Pain VAS, BPI-Severity, and BPI-Interference, respectively. EQ-5D-5L index value improved from 0.38 ± 0.36 at baseline to 0.62 ± 0.26 at 24 months (p < 0.001). Fifty-five adverse events were reported by five patients (4.31%), of which 78.18% (n = 43) were mild-to-moderate in severity; no life-threatening or fatal events occurred.Conclusion This study highlights the potential of CBMPs as an alternative to opioid treatment. Though this study builds on the limited body of evidence through strong external validity, future clinical trials is still required to conclusively determine the efficacy of CBMPs.