ASCO expert panel rules against cannabis for cancer patients


By Mardi Chapman

27 Mar 2024

Access to medical cannabis and cannabinoids has outpaced the science supporting their clinical use in adults with cancer, the latest ASCO guideline says.

The American Society of Clinical Oncology guideline recommends against the use of cannabis and/or cannabinoids to augment cancer-directed treatment unless in the context of a clinical trial and strongly against the use of cannabis and/or cannabinoids in place of cancer-directed treatment.

It also noted that cannabis and/or cannabinoids may cause significant clinical and financial toxicities without good-quality evidence of clinical benefit.

Published in the Journal of Clinical Oncology [link here], the guideline conducted by a multidisciplinary ASCO Expert Panel is underpinned by a systematic review of the literature including 11 previous systematic reviews.

Despite finding a lack of evidence for benefit and warning of potential harm, the guideline recommends a softly-softly approach to communicating with patients about cannabis.

“Given the high prevalence of cannabis and/or cannabinoid use among adults with cancer, clinicians should routinely and nonjudgmentally inquire about cannabis use (or consideration of use) and either guide care or direct adults with cancer to appropriate resources,” one of the recommendations said.

“These conversations should omit pejorative terms commonly associated with substance use (eg, user, addict) and reflect the language used by the adult with cancer and their caregiver.”

The guideline included a weak recommendation for cannabis and/or cannabinoids in refractory, chemotherapy-induced nausea and vomiting (CINV) when added to guideline-concordant anti-emetic regimens.

They referenced a positive Australian study, previously reported in the limbic and listed in related articles below.  

However, other evidence was insufficient to recommend for or against cannabis and/or cannabinoids in managing other cancer treatment-related toxicities or symptoms including cancer pain.

The guidelines also warned against use of ≥300 mg/day oral CBD to manage cancer symptom burden “due to lack of proven efficacy and risk for reversible liver enzyme abnormalities.”

Call for more research 

The Expert Panel highlighted the knowledge gaps regarding use of cannabis and/or cannabinoids in cancer care and identified future research questions and priorities. They included:

  • the optimal mode of cannabis administration when targeting refractory CINV
  • whether cannabis can reduce opioid requirements in cancer-related pain
  • cannabis as prevention or treatment of chemotherapy-induced peripheral neuropathy
  • the impact of cannabis use on sleep, fatigue and sleep architecture
  • the acute and chronic neuropsychiatric impacts of cannabis and/or cannabinoid use
  • symptom management and care of children, adolescents and young adults with cancer.

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