Misleading Information: Marijuana decreases risk of lung cancer

"Marijuana decreases risk" is a bit misleading. It is also an example of one of the reasons I dislike the "pro-marijuana"   promotions, though I hold no position at this point as to whether it should be legalized or not. 

Smell the Truth, a marijuana advocacy group, reported a couple days ago:

• As more and more Americans consider the pros and cons of cannabis legalization, many points are worth repeating, and chief among them: cannabis actually decreases the risk of lung cancer.

It uses as one of its sources the results of a research effort by Donald Tashman:

• LA Weekly managed to quote one of the nation’s leading pulmonologists, Dr. Donald Tashkin. The professor emeritus of medicine at UCLA once sought to prove pot causes lung cancer, but the evidence forced him to conclude the opposite.

However, when the Tashman findings were originally reported, it stated:

• The largest study of its kind has unexpectedly concluded that smoking marijuana, even regularly and heavily, does not lead to lung cancer. The new findings "were against our expectations," said Donald Tashkin of the University of California at Los Angeles, a pulmonologist who has studied marijuana for 30 years.  [Washington Post]
  

So marijuana, in and of itself, does not decrease any lung cancer risk. But, it is less of a risk then using regular tobacco cigarettes according to  what the original Tashman report said. So don't go seeking out marijuana thinking it will decrease your chances of getting lung cancer.

Tashman did say this at one point:

• "We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use," he said. "What we found instead was no association at all, and even a suggestion of some protective effect."  [Washington Post]

But there was never any information divulged which  showed that to be true.

Wikipedia notes Tashman with this summary:

• In 2006, he was in charge of a large case-control study on marijuana and the risk of cancer. Contrary to his group's expectations, the study found no increase in lung cancer risk even among heavy users of marijuana