Antitumor Effects of Cannabinoids

One study in mice and rats suggested that cannabinoids may have a protective effect against the development of certain types of tumors. During this 2-year study, groups of mice and rats were given various doses of THC by gavage. A dose-related decrease in the incidence of hepatic adenoma tumors and hepatocellular carcinoma was observed in the mice. Decreased incidences of benign tumors (polyps and adenomas) in other organs (mammary gland, uterus, pituitary, testis, and pancreas) were also noted in the rats. In another study, delta-9-THC, delta-8-THC, and cannabinol were found to inhibit the growth of Lewis lung adenocarcinoma cells in vitro and in vivo . In addition, other tumors have been shown to be sensitive to cannabinoid-induced growth inhibition.

Cannabinoids may cause antitumor effects by various mechanisms, including induction of cell death, inhibition of cell growth, and inhibition of tumor angiogenesis and metastasis. Cannabinoids appear to kill tumor cells but do not affect their nontransformed counterparts and may even protect them from cell death.


Myth: Marijuana is More Damaging to the Lungs Than Tobacco. Marijuana smokers are at a high risk of developing lung cancer, bronchitis, and emphysema.

Fact: In a retrospective cohort study of 64,855 men aged 15 to 49 years, participants were divided into cohorts based on their use of tobacco and marijuana: never inhaled either, inhaled only Cannabis, inhaled only tobacco, and inhaled tobacco and Cannabis.[5] Among the nonsmokers, two cases of lung cancer were diagnosed during the follow-up period. Among the men who inhaled tobacco either alone or in addition to marijuana, the risk of lung cancer increased tenfold. In the follow-up of men who inhaled marijuana alone, no cases of lung cancer were documented.

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