Smoking Marijuana Does Not Cause Lung Cancer

Marijuana smoking -”even heavy longterm use”- does not cause cancer of the lung, upper airwaves, or esophagus, Donald Tashkin reported at this year’s meeting of the International Cannabinoid Research Society. Coming from Tashkin, this conclusion had extra significance for the assembled drug-company and university-based scientists ( most of whom get funding from the U.S. National Institute on Drug Abuse ). Over the years, Tashkin’s lab at UCLA has produced irrefutable evidence of the damage that marijuana smoke wreaks on bronchial tissue. With NIDA’s support, Tashkin and colleagues have identified the potent carcinogens in marijuana smoke, biopsied and made photomicrographs of pre-malignant cells, and studied the molecular changes occurring within them. It is Tashkin’s research that the Drug Czar’s office cites in ads linking marijuana to lung cancer.

There was time for only one question, said the moderator, and San Francisco oncologist Donald Abrams, M.D., was already at the microphone: “You don’t see any positive correlation, but in at least one category [marijuana-only smokers and lung cancer], it almost looked like there was a negative correlation, i.e., a protective effect. Could you comment on that?”

“Yes,” said Tashkin. “The odds ratios are less than one almost consistently, and in one category that relationship was significant, but I think that it would be difficult to extract from these data the conclusion that marijuana is protective against lung cancer. But that is not an unreasonable hypothesis.”