A review of 77 case reports found only 14% provided strong evidence for anticancer effects of cannabis, while 81% were weak, and no strong clinical trial data exist despite over 100 preclinical studies.
Cancer patients, oncologists, and anyone encountering claims about cannabis curing cancer.
Only 14% of case reports met strong evidence criteria; 81% were weak
What the researchers found
Of 207 pre-clinical articles, 107 contained original data showing anticancer activity. Of 77 published case reports, only 14% met strong criteria (active cancer, validated response, no concurrent treatment), 5% were moderate, and 81% were weak. CBD was the most reported anticancer cannabinoid (10-800 mg/day). Two small trials reported survival data for glioblastoma. Nearly 40% of cancer patients using cannabis believe it will treat their cancer.
Why it matters
Numerous anecdotal reports shared on social media create unrealistic expectations. This systematic appraisal shows that most published case reports do not meet basic evidence standards.
The numbers in context
207 pre-clinical articles, 107 with original data. 77 case reports: 14% strong, 5% moderate, 81% weak. CBD doses: 10-800 mg/day. THC doses: 4.8-7.5 mg. 10% of cases were pediatric.
How the study worked
Literature review of PubMed, EBSCO, ClinicalTrials.gov, online sources, and books. All case reports appraised as weak, moderate, or strong based on three criteria: active cancer at cannabis administration, validated lab/radiographic responses, and cannabis use without concurrent anticancer treatments.
What this study cannot tell us
Case reports inherently cannot prove causation. Strong criteria were defined by the authors. Publication bias favors positive case reports. Online anecdotal claims were not systematically assessed.
How to read the evidence
Systematic appraisal of available clinical evidence revealing that most published reports are insufficient to support anticancer claims.
When this study was published
Published in 2022.
The bigger picture
The disconnect between over 100 positive preclinical studies and the lack of strong clinical evidence highlights the difficulty of translating lab findings to human cancer treatment.
Questions still open
- Would controlled clinical trials show anticancer effects of cannabinoids in specific cancers? Are patients using cannabis in place of proven cancer treatments based on weak anecdotal evidence?
Common questions
Can cannabis cure cancer?
Should cancer patients use cannabis instead of standard treatment?
Read the original research
Cannabis as an Anticancer Agent: A Review of Clinical Data and Assessment of Case Reports.
Cannabis and cannabinoid research, 7(1), 24-33
Citation
Guggisberg, Jordan; Schumacher, Megan; Gilmore, Grace; Zylla, Dylan M. (2022). Cannabis as an Anticancer Agent: A Review of Clinical Data and Assessment of Case Reports.. Cannabis and cannabinoid research, 7(1), 24-33. https://doi.org/10.1089/can.2021.0045
Explore the wider topic
- CBD Oil Quality Guide: How to Avoid Snake Oil
- Anxiety After Quitting Weed: When to Consider Medication
- Cannabis for Chemotherapy Nausea: What the Evidence Actually Shows
- Cannabis for Chronic Pain: What the Research Actually Supports
- Cannabis and Epilepsy: The Epidiolex Story and What It Means
- Does CBD Actually Work for Anxiety? What the Evidence Shows
- Does CBD Help with Weed Withdrawal? What Studies Show
- CBD vs THC: The Differences That Actually Matter
- The Proven Medical Benefits of Cannabis: What Research Supports
- Quitting Weed Before Surgery
- Weed and Medications: What Changes When You Quit
- Quitting Weed During Pregnancy: What You Need to Know
- Quitting Weed While Pregnant: What You Need to Know
- Cannabis and Older Adults: Risks Seniors Should Know
- Cannabis and Breastfeeding: THC in Breast Milk