Cannabis for Cancer and Pain
Cancer patients are faced with a number of distressing symptoms that may be amenable to treatment with cannabis and related therapies including chemotherapy-related nausea and vomiting, anorexia/cachexia, pain, anxiety/depression and insomnia. Delta-9-tetrahydrocannabinol (THC) was licensed and approved in 1986 in the US for treatment of chemotherapy-induced nausea and vomiting. Many patients, however, prefer using the whole plant for this indication although clinical trial results have not been conclusive. Cannabis is the only anti-emetic which also increases appetite.
Much of the physiology of the endocannabinoid system and cannabinoid receptors would predict a role for cannabinoids in modulation of pain. Clinical trials have demonstrated a benefit for cannabis over placebo in patients with HIV-related painful peripheral neuropathy. Preclinical studies suggest that cannabinoids may be useful in both prevention and treatment of chemotherapy-induced peripheral neuropathy. To date, one small pilot study of the sublingual whole plant extract – nabiximols- has suggested a potential benefit for this indication. In preclinical models, cannabinoids have been shown to be synergistic with opioids in pain relief. A small pharmacokinetic interaction study demonstrated the safety of adding vaporized cannabis to a stable dose of sustained-release opiates with some suggestion of increased analgesia.
Increasing in vitro evidence suggests that cannabinoids – particularly delta-9-tetrahydrocannabinol and the non-psychoactive anti-inflammatory cannabidiol- may have some direct anti-cancer activity. Animal studies are also supporting this possibility. These effects may be mediated by way of cannabinoid receptor interactions inducing programmed cell death. In addition, cannabinoids may decrease angiogenesis by modulating vascular endothelial growth factor (VEGF) as well as inhibiting matrix metalloproteinase-2 which is involved in modulating tumor invasiveness and metastasis. Although no clinical trials have been conducted in humans, an increasing number of patients with malignant diagnoses are seeking cannabis cancer “cures”.