Pubdate: Sat, 3 May 2008
Source: CounterPunch (US Web)
Copyright: 2008 CounterPunch
Website: 
Details: 
Author: Fred Gardner
Bookmark:  (Dr.  Tashkin)

STUDY: SMOKING POT DOESN'T CAUSE CANCER--IT MAY PREVENT IT!

The Greatest Story Never Told

Smoking Cannabis Does Not Cause Cancer Of Lung or Upper Airways, 
Tashkin Finds; Data Suggest Possible Protective Effect

The story summarized by that headline ran in O'Shaughnessy's (Autumn 
2005), CounterPunch, and the Anderson Valley Advertiser. Did we win 
Pulitzers, dude? No, the story was ignored or buried by the corporate 
media. It didn't even make the "Project Censored" list of 
under-reported stories for 2005. "We were even censored by Project 
Censored," said Tod Mikuriya, who liked his shot of wry.

It's not that the subject is trivial. One in three Americans will be 
afflicted with cancer, we are told by the government (as if it's our 
immutable fate and somehow acceptable). Cancer is the second leading 
cause of death in the U.S. and lung cancer the leading killer among 
cancers. You'd think it would have been very big news when UCLA 
medical school professor Donald Tashkin revealed that components of 
marijuana smoke -although they damage cells in respiratory tissue- 
somehow prevent them from becoming malignant. In other words, 
something in marijuana exerts an anti-cancer effect.

Tashkin has special credibility. He was the lead investigator on 
studies dating back to the 1970s that identified the components in 
marijuana smoke that are toxic. It was Tashkin et al 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.

Tashkin reviewed his findings April 4 at a conference organized by 
"Patients Out of Time," a reform group devoted to educating doctors 
and the public (as opposed to lobbying politicians). Some 30 MDs and 
nurses got continuing medical education credits for attending.

The National Institute on Drug Abuse supported Tashkin's 
marijuana-related research over the decades and readily 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. 
(Tashkin is to marijuana as a cause of lung cancer what Hans Blick is 
to Iraq's weapons of mass destruction -an honest investigator who set 
out to find something, concluded that it wasn't there, and reported 
his results.)

Tashkin's team interviewed 1,212 cancer patients from the Los Angeles 
County Cancer Surveillance program, matched for age, gender, and 
neighborhood with 1,040 cancer-free controls. Marijuana use was 
measured in "joint years" (number of years smoked times number of 
joints per day). It turned out that increased marijuana use did not 
result in higher rates of lung and pharyngeal cancer (whereas tobacco 
smokers were at greater risk the more they smoked). Tobacco smokers 
who also smoked marijuana were at slightly lower risk of getting lung 
cancer than tobacco-only smokers.

These findings were not deemed worthy of publication in "NIDA Notes." 
Tashkin reported them at the 2005 meeting of the International 
Cannabinoid Research Society and they were published in the October 
2006 issue of Cancer Epidemiology Biomarkers & Prevention. Without a 
press release from NIDA calling attention to its significance, the 
assignment editors of America had no idea that "Marijuana Use and the 
Risk of Lung and Upper Aerodigestive Tract Cancers: Results of a 
Population-Based Case-Control Study" by Mia Hashibe1, Hal 
Morgenstern, Yan Cui, Donald P. Tashkin, Zuo-Feng Zhang, Wendy Cozen, 
Thomas M. Mack and Sander Greenland was a blockbuster story.

I suggested to Eric Bailey of the L.A. Times that he write up 
Tashkin's findings -UCLA provided the local angle if the anti-cancer 
effect wasn't enough. Bailey said his editors wouldn't be interested 
for some time because he had just filed a marijuana-related piece 
(about the special rapport Steph Sherer of Americans for Safe Access 
enjoyed with some old corporado back in Washington, D.C.) The Tashkin 
scoop is still there for the taking!

Investigators from New Zealand recently got widespread media 
attention for a study contradicting Tashkin's results. "Heavy 
cannabis users may be at greater risk of chronic lung disease 
-including cancer-compared to tobacco smokers," is how BBC News 
summed up the New Zealanders' findings. The very small size of the 
study -79 smokers took part, 21 of whom smoked cannabis only-was not 
held against the authors. As conveyed in the corporate media, the New 
Zealand study represented the latest word on this important subject 
(as if science were some kind of tennis match and the truth just gets 
truthier with every volley).

Tashkin criticized the New Zealanders' methodology in his talk at 
Asilomar: "There's some cognitive dissonance associated with the 
interpretation of their findings. I think this has to do with the 
belief model among the investigators and -I wish they were here to 
defend themselves-the integrity of the investigators... They actually 
published another paper in which they mimicked the design that we 
used for looking at lung function."

Tashkin spoke from the stage of an airy redwood chapel designed by 
Julia Morgan. He is pink-cheeked, 70ish, wears wire-rimmed 
spectacles. "For tobacco they found what you'd expect: a higher risk 
for lung cancer and a clear dose-response relationship. A 24-fold 
increase in the people who smoked the most... What about marijuana? 
If they smoked a small or moderate amount there was no increased 
risk, in fact slightly less than one. But if they were in the upper 
third of the group, then their risk was six-fold... A rather 
surprising finding, and one has to be cautious about interpreting the 
results because of the very small number of cases (14) and controls (4)."

Tashkin said the New Zealanders employed "statistical sleight of 
hand." He deemed it "completely implausible that smokers of only 365 
joints of marijuana have a risk for developing lung cancer similar to 
that of smokers of 7,000 tobacco cigarettes... Their small sample 
size led to vastly inflated estimates... They had said 'it's ideal to 
do the study in New Zealand because we have a much higher prevalence 
of marijuana smoking.' But 88 percent of their controls had never 
smoked marijuana, whereas 36% of our controls (in Los Angeles) had 
never smoked marijuana. Why did so few of the controls smoke 
marijuana? Something fishy about that!"

Strong words for a UCLA School of Medicine professor!

As to the highly promising implication of his own study -that 
something in marijuana stops damaged cells from becoming malignant- 
Tashkin noted that an anti-proliferative effect of THC has been 
observed in cell-culture systems and animal models of brain, breast, 
prostate, and lung cancer. THC has been shown to promote known 
apoptosis (damaged cells die instead of reproducing) and to counter 
angiogenesis (the process by which blood vessels are formed -a 
requirement of tumor growth). Other antioxidants in cannabis may also 
be involved in countering malignancy, said Tashkin.

Much of Tashkin's talk was devoted to Chronic Obstructive Pulmonary 
Disease, another condition prevalent among tobacco smokers. Chronic 
bronchitis and emphysema are two forms of COPD, which is the fourth 
leading cause of death in the United States. Air pollution and 
tobacco smoke are known culprits. Inhaled pathogens cause an 
inflammatory response, resulting in diminished lung function. COPD 
patients have increasing difficulty clearing the airways as they get older.

Tashkin and colleagues at UCLA conducted a major study in which they 
measured lung function of various cohorts over eight years and found 
that tobacco-only smokers had an accelerated rate of decline, but 
marijuana smokers -even if they smoked tobacco as well-experienced 
the same rate of decline as non-smokers. "The more tobacco smoked, 
the greater the rate of decline," said Tashkin. "In contrast, no 
matter how much marijuana was smoked, the rate of decline was similar 
to normal." Tashkin concluded that his and other studies "do not 
support the concept that regular smoking of marijuana leads to COPD."

Hope that makes you breathe easier.