You'd think it would have been very big news in the spring of 2005 when Donald Tashkin, a professor of pulmonology at UCLA's David Geffin School of Medicine, revealed at a conference that components of marijuana smoke, although they damage cells in respiratory tissue, somehow prevent them from becoming malignant. But headlines announcing "Pot Doesn't Cause Cancer" did not ensue.
Tashkin will review his findings and discuss current research this Thursday in Santa Monica, California as part of a course for doctors accredited by the University of California San Francisco. (It is open to the public; pre-registration is $95.)
Tashkin has special credibility. He was the lead investigator on studies dating back to the 1970s that identified the compounds in marijuana smoke that are toxic. It was Tashkin who published photomicrographs showing that marijuana smoke damages cells lining the upper airways. It was the Tashkin lab reporting that benzpyrene -- a component of tobacco smoke that plays a role in most lung cancers -- is especially prevalent in marijuana smoke. It was Tashkin's data documenting that marijuana smokers are more likely than non-smokers to cough, wheeze and produce sputum.
The National Institute on Drug Abuse supported Tashkin's marijuana-related research over the decades and gave him a grant to conduct a large, population-based, case-controlled study that would prove definitively that heavy, long-term marijuana use increases the risk of lung and upper-airways cancers. What Tashkin and his colleagues found, however, disproved their hypothesis.