Cannabis users may have significantly lower odds of developing oral cancer, according to a new analysis that pooled data from six case-control studies involving over 15,000 participants.
The meta-analysis study, conducted by researchers from Jordan, Iraq, and Uzbekistan, examined 15,056 participants – 4,686 with oral cancer and 10,370 without – to investigate the relationship between cannabis use and oral cancer risk.
“Following PRISMA guidelines, we conducted comprehensive searches across Scopus, PubMed, Web of Science, and Embase databases up to August 2025. We included only case-control studies reporting quantitative risk estimates for marijuana use and histologically confirmed oral cancer,” wrote the study author.
Researchers pooled the data from the previous six studies to show an inverse relationship between cannabis use and oral cancer. The association showed an odds ratio of 0.659, which means there is a 34% lower risk of a cannabis user developing oral cancer than a non-cannabis user.
The data was regarded by the Jordan-based researchers as “statistically significant,” meaning that they considered the 34% figure to be too high to be attributed to chance alone.
Researchers failed to find a dose-responsive relationship in the data, which shows that using higher doses of cannabis did not produce a higher level of protection from oral cancer.
“Subgroup analyses were performed based on the duration of use, gender, and age at initiation of marijuana use; however, no clear dose-response relationship was observed,” the author noted.
The findings add to growing evidence of cannabis’s potential health effects. A recent study from Thailand found that patients with aggressive cancers who used cannabis in palliative care survived longer than those who did not.
Researchers called for more investigations to produce more solid conclusions.
“This meta-analysis suggests marijuana use is associated with reduced oral cancer risk. However, given methodological limitations, heterogeneity in exposure assessment, and conflicting recent evidence, these findings require cautious interpretation. Future large-scale prospective cohort studies with standardized exposure measurements are essential for definitive conclusions,” the study said.
