OBJECTIVE

Historically cannabinoids have been used for both therapy and recreation, yet the elucidation of the endocannabinoid system and their chemistry has been relatively recent. Prohibition of cannabis has meant few clinical trials, especially in cancer pain. This review will consider previous animal and clinical data and assess more recent investigations of clinical effectiveness of cannabinoids in pain and specifically cancer pain.

RESULTS

Meta-analyses based on historical studies question the utility of cannabinoids in pain due to modest analgesia and problematic central side effects. However, there has been a resurgence in clinical trials of cannabis extracts and analogues. New data have contributed to the understanding of how cannabinoids work and proposed how to obtain analgesia unfettered by adverse effects. Moreover, recent clinical trials have demonstrated the current role of cannabinoids may be to attain small but significant benefit in refractory chronic and cancer pain.

CONCLUSIONS

Cannabinoids may be a useful addition to current analgesic treatments. The evidence supports a possible role for cannabinoids in refractory cancer pain. However, to realize the full potential of cannabinoids suggested by preclinical data, it is likely that peripheral CB1 or CB2 receptors or modulation of endocannabinoids will have to be targeted to achieve analgesia without dose limiting side effects.