Cannabis for cancer – illusion or the tip of an iceberg: a review of the evidence for the use of Cannabis and synthetic cannabinoids in oncology

ABSTRACT

Introduction: A flowering plant of variegated ingredients and psychoactive qualities, Cannabis has long been used for medicinal and recreational purposes. Regulatory approvals have been gained across a broad range of palliative and therapeutic indications, and in some cases, included in standard treatment guidelines.

Areas covered: The use of Cannabis and cannabinoid-based-medicines in oncology is summarized in this article. Cannabinoids are classified according to natural and synthetic subtypes and their mechanisms of action expounded. The variability of available products is discussed in the clinical context and data regarding chemotherapy-induced nausea and vomiting, cancer-related pain, anorexia, insomnia, and anxiety are presented. Moreover, immunological and antineoplastic effects in preclinical and clinical trials are addressed. Concepts such as synergism or opposition with conventional treatment modalities, the sequence of administration and dosage, molecular cross-talk and malignancy-cannabinoid congruence, are explored. Finally, side-effects, limitations in trial design and legislation barriers are related.

Expert opinion: Sufficient evidence supports the use of Cannabis for palliative indications in oncology; however, patients should be carefully selected, guided and followed. Promising research suggests the potent antineoplastic activity, but more data must be accrued before conclusions can be drawn.

Trial registration: ClinicalTrials.gov identifier: NCT01812603.

Trial registration: ClinicalTrials.gov identifier: NCT01489826.

Trial registration: ClinicalTrials.gov identifier: NCT01654497.

KEYWORDS:

• Cannabis
• medical marijuana
• cancer
• nausea and vomiting
• pain
• palliative oncology
• anti-neoplastic
• immunology
• drug interactions

Article highlights

• Cannabis has historically been used as a healing herb and mild-altering plant and is currently approved in many countries for recreational and medicinal use.

• Favorable outcomes are shown in chemotherapy-induced nausea and vomiting and cancer pain, with evidence of advantageous neurological interactions.

• Cannabinoids have shown antineoplastic effects in preclinical studies in a wide range of cancer cells and some animal models, and distinct signaling pathways are implicated in these results.

• Conflicting reports show that Cannabis contains immunosuppressive properties and oncogenic potential.

• Combining Cannabis with conventional cancer treatment modalities may cause enhancing or diminishing effects.

• Research is hampered by high variability and lack of standardization in trial construction and drug formulation and pharmacodynamics.

• Clinical trials and in-depth drug and patient analyses are needed to find the right constellation of drug composition, dose, and means of administration, to tailor specific Cannabis-based medicine per indication and per patient.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose

Additional information

Funding

This paper was not funded.