Can cannabis kill cancer cells? What does the research actually show?

Cannabinoids do kill cancer cells in laboratory settings — this is well-established in preclinical research. The mechanisms include: induction of apoptosis via ceramide synthesis and ER stress; inhibition of angiogenesis (tumor blood vessel formation); reduction of tumor cell migration and invasion; and autophagy induction. These effects have been demonstrated across glioblastoma, breast, prostate, colorectal, and lung cancer cell lines. However, three critical caveats apply: (1) The concentrations required (typically 5–20μM) are far higher than achievable in human plasma with any practical dosing regimen. (2) Some studies show paradoxical pro-tumor effects at lower, clinically relevant concentrations — particularly via CB2-mediated immunosuppression. (3) Zero human RCTs have demonstrated anti-tumor efficacy. The gap between cell-line results and human outcomes is enormous. Patients should not use cannabis as a cancer treatment or delay proven therapies based on this preclinical data.