"The largest study ever conducted on marijuana’s relevance to lung cancer has come up with some somewhat surprising results. The National Institutes of Health’s National Institute on Drug Abuse funded the University of California at Los Angeles study, which found that smoking marijuana does not cause lung cancer, and it doesn’t seem to matter how much or how often it is smoked." Addicting Info – Study Demonstrates Smoking Pot Doesn’t Cause Lung Cancer, No Matter The Frequency Or Amount.