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Keywords:

  • cancer;
  • cannabis;
  • chemotherapy;
  • meta-analysis;
  • randomized clinical trial;
  • systematic review

This paper aims to evaluate the anti-emetic efficacy of cannabinoids in cancer patients receiving chemotherapy using a systematic review of literature searched within electronic databases such as PUBMED, EMBASE, PSYCINFO, LILACS, and ‘The Cochrane Collaboration Controlled Trials Register’. Studies chosen were randomized clinical trials comprising all publications of each database until December 2006. From 12 749 initially identified papers, 30 fulfilled the inclusion criteria for this review, with demonstration of superiority of the anti-emetic efficacy of cannabinoids compared with conventional drugs and placebo. The adverse effects were more intense and occurred more often among patients who used cannabinoids. Five meta-analyses were carried out: (1) dronabinol versus placebo [n = 185; relative risk (RR) = 0.47; confidence interval (CI) = 0.19–1.16]; (2) Dronabinol versus neuroleptics [n = 325; RR = 0.67; CI = 0.47–0.96; number needed to treat (NNT) = 3.4]; (3) nabilone versus neuroleptics (n = 277; RR = 0.88; CI = 0.72–1.08); (4) levonantradol versus neuroleptics (n = 194; RR = 0.94; CI = 0.75–1.18); and (5) patients' preference for cannabis or other drugs (n = 1138; RR = 0.33; CI = 0.24–0.44; NNT = 1.8). The superiority of the anti-emetic efficacy of cannabinoids was demonstrated through meta-analysis.