Marijuana Myth Debunk - Actually, some research has suggested that the non psychoactive ingredients in marijuana could possibly kill cancer cells. When these ingredients were applied to leukemia cells in a laboratory setting, metastasis was halted in several leukemia cells. With light or moderate use of marijuana, there's no link between lighting up and lung cancer. Plus, medical marijuana is part and parcel of treatment for some cancer patients. - A scientist at the University of London's St. George School of Medicine