As marijuana becomes more accepted -- and in some places, legal -- a UCLA researcher has reexamined the question: does smoking marijuana cause lung cancer?
In the June edition of Annals of the American Thoracic Society, Donald P. Tashkin, MD, emeritus professor of medicine at UCLA's David Geffen School of Medicine, says that light to moderate marijuana use does not cause increased lung cancer risk and that the verdict is not out on heavy use.
"Findings from a limited number of well-designed epidemiological studies do not suggest an increased risk for the development of either lung or upper airway cancer from light or moderate use, although evidence is mixed concerning possible carcinogenic risks of heavy, long-term use," Tashkin said in a summary of his article.
Marijuana does, however, "cause visible and microscopic injury to the large airways that is consistently associated with an increased likelihood of symptoms of chronic bronchitis that subside after cessation of use," according to Tashkin.
But even heavy marijuana use has "far lower risks for pulmonary complications" than the consequences of tobacco use, Tashkin said.
Tashkin authored a similar paper in 2006 that also found no link between marijuana use and risk of lung cancer.
He's among several researchers who have published recently on the topic of marijuana and cancer. Last year, a pair of scientists at California Pacific Medical Center in San Francisco found that a compound derived from marijuana could stop metastasis in many kinds of aggressive cancers, potentially altering the fatality of the disease forever.
Earlier this year, Kaiser Permanente researchers found that people who smoke marijuana may be less likely to get bladder cancer than those who smoke cigarettes.