Cannabis and Cancer Risk – New Systematic Review

November 29, 2019

Cannabis and Cancer – New Review and Meta-Analysis

On November 27, 2019 a new review and meta-analysis was published in JAMA Open:

Quick summary for those who don’t have time to read it:

  1. Review of cancer rates in studies where people had to use at least 1 joint-year experience (equivalent to 1 joint per day for 1 year)
  2. They found 25 English language studies
  3. In 3 case-control studies, of more than 10 years of cannabis use there was an association with cannabis use and testicular germ cell tumour (TGCT) (OR, 1.36;95% CI 1.03-1.81)
  4. Evaluations of ever use generally found no association with cancers
  5. Findings for lung cancer were mixed, confounded by few marijuana-only smokers, poor exposure assessment, and inadequate adjustment

Bottom Line for Practice:

Early studies have not been shown to conclusive link cannabis use and cancer.  Low-strength evidence suggests that smoking cannabis may be associated with developing TGCT (correlation but not causation, at this point).  More long-term studies with cannabis only smokers would hopefully provide better understanding of the potential risk with other cancers.