NEW YORK (Reuters Health) - You've heard about using marijuana and drugs derived from it to keep some of the side effects of toxic cancer chemotherapy in check. But what if smoking marijuana for 10 to 20 years could actually protect against certain tumors?












It's unclear why marijuana would prevent cancer, if in fact the study is borne out by others, but the authors note that chemicals in pot called cannabinoids have been shown to have potential antitumor effects. Other studies have linked marijuana use to a reduced risk of some cancers, such as cancer of the prostate, and now head and neck cancer.




Overall, however, research on the effects of marijuana on human health is mixed. Some studies have suggested the drug can increase a person's risk of heart attack or stroke and cause some cancers such as lung cancer.


In the journal Cancer Prevention Research, the researchers emphasize that further research from larger studies is needed to verify this link. Moreover, even if marijuana use were found to protect against these cancers, the risks of use may still outweigh this benefit, they say.


"Marijuana is an entry-level drug and can be associated with later use of more serious addictive drugs, as well as other risk behaviors," warn Dr. Karl T. Kelsey, from Brown University, Providence, Rhode Island, and colleagues.


Any policy regarding marijuana use should take this into consideration "and should not be made based on one study's results," they note.