Researchers from Canada, the United States and New Zealand pooled data from six previous studies spanning more than 2,000 lung cancer cases and nearly 3,000 controls to determine whether cannabis use was associated with lung cancer. Even when data was analyzed based on intensity, duration, consumption and age of initiation, no significant association was found.
Why is that?
Hal Morgenstern, PhD, a University of Michigan epidemiologist and co-author of the latest study, suggests it might be that most marijuana users don’t smoke enough of it to get sick. Others who have studied the link between marijuana and lung cancer, such as Donald P. Tashkin, MD, a lung specialist from the University of California, point to an often overlooked difference between marijuana and tobacco — certain compounds in marijuana have been shown to have anti-cancer effects.
Similarly, one of Dr. Tashkin’s own studies, published in 2006, found that while heavy tobacco smokers experienced up to a 20-fold increase in lung cancer risk, even the most frequent users of cannabis were no more likely to develop lung cancer than the average person.