A systematic review of medicinal cannabis pharmacology in oncology found only 18 relevant studies and virtually no data on absorption in cancer populations, revealing a critical gap in dosing knowledge.
Oncologists, pharmacologists, and cancer patients using medicinal cannabis.
Only 4 studies had absorption data
What the researchers found
Of 18 selected articles (10 RCTs, 2 experimental, 2 retrospective cohort, 4 case studies), only 4 reported absorption data and only 1 drug interaction study was identified. There is almost no evidence on the pharmacokinetics of medicinal cannabis specifically in cancer patients.
Why it matters
Without absorption data, cannabis dosing in cancer patients is essentially guesswork. Cancer patients may metabolize cannabinoids differently due to their disease, other medications, and compromised organ function, making this gap particularly dangerous.
The numbers in context
18 articles selected: 10 RCTs, 2 experimental, 2 retrospective cohort, 4 case studies. Only 4 reported absorption data. Only 1 drug interaction study found.
How the study worked
Systematic literature review across six databases for studies reporting pharmacological data on medicinal cannabis in oncology.
What this study cannot tell us
Systematic review can only identify what has been studied. The lack of pharmacokinetic data may partly reflect the difficulty of conducting such studies in cancer populations and the challenges of cannabinoid analytical methods.
How to read the evidence
Rated preliminary because the review reveals a near-total absence of pharmacokinetic evidence rather than providing positive findings.
When this study was published
Published in 2019. Some additional pharmacokinetic research may have been conducted since.
The bigger picture
Cannabis is increasingly used by cancer patients, but the pharmaceutical basics, how much gets absorbed, how it interacts with chemotherapy, and how disease state affects metabolism, are almost entirely unknown. This is remarkable for a substance used by millions of patients.
Questions still open
- How do cancer-related changes in liver and GI function affect cannabis absorption? What are the drug interactions between cannabinoids and common chemotherapy regimens? Should dosing be adjusted based on cancer type or treatment?
Common questions
Do we know how cannabis works in cancer patients?
Why is this gap important?
Read the original research
Pharmacological evidence of medicinal cannabis in oncology: a systematic review.
Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 27(9), 3195-3207
Citation
Brown, Danielle; Watson, Michael; Schloss, Janet. (2019). Pharmacological evidence of medicinal cannabis in oncology: a systematic review.. Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 27(9), 3195-3207. https://doi.org/10.1007/s00520-019-04774-5
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