Cannabis and Cancer

The cannabis genus including the species sativa, indica, and ruderalis, has been used for its psychoactive and medicinal properties for nearly 5000 years.¹ Marijuana consists of dried flower buds and hashish is a block of cannabis resin. Different strains and growing conditions can affect the biologic activity of cannabis. Cannabis contains over 100 different cannabinoids, which are 21-carbon terpenophenolic compounds that bind to cannabinoid receptors, potentially eliciting biologic effects.²

Cannabis and its synthetic cannabinoids have been studied for medicinal properties across multiple disease states. The cannabinoids delta-9-tetrahydrocannaibinol (THC) and cannabidiol (CBD) are probably the most extensively studied, but other synthetic cannabinoids have also been studied. In addition, dronabinol and nabilone are approved by the U.S. Food and Drug Administration (FDA) for the treatment of breakthrough chemotherapy-induced nausea and vomiting (CINV), and dronabinol is also indicated for the treatment of cancer-related anorexia. Additional studies have evaluated cannabis for the treatment of pain, cachexia, and anticancer properties.

Supportive Care for Cancer

There are few studies that evaluated the effect of smoke or ingested marijuana for the treatment of cancer-related conditions. Most studies used cannabinoids or extracts.

CINV

The rationale underlying the use of cannabinoids for the prevention or treatment of CINV stems from the location of endocannabinoid receptors, which are interspersed with emetic reflex pathways.¹ A meta-analysis demonstrated that synthetic THC dronabinol was superior to neuroleptics and was synergistic with prochlorperazine. Another meta-analysis demonstrated that cannabinoids were more effective than prochlorperazine, metoclopramide, chlorpromazine, thiethylperazine, haloperidol, domperidone, or alizapride.² A blinded, placebo-controlled study found that cannabidiol was noninferior to 5-HT₃ antagonists, and may be more effective against anticipatory CINV.¹ Smoked marijuana was effective in a small study of patients who received high-dose methotrexate, but smoked marijuana or oral THC were not effective in improving CINV among patients receiving doxorubicin and cyclophosphamide.³ Cannabis has not yet been compared with the newer antiemetics, such as the NK1 receptor antagonists.

The National Comprehensive Cancer Network (NCCN) guideline recommends dronabinol or nabilone as options for the treatment of breakthrough CINV, though does not discuss the studies that support this recommendation.⁴