Pubdate: Fri, 21 Aug 2009
Source: AlterNet (US Web)
Copyright: 2009 Marijuana Policy Project
Author: Bruce Mirken
Note: Bruce Mirken is communications director for the Marijuana Policy Project.


New Study Finds That Marijuana Smokers Have a Lower Risk of Head and 
Neck Cancers.

Among the more interesting pieces of news that came out while I was 
on vacation the first half of August was a new study in the journal 
Cancer Prevention Research, which found that marijuana smokers have a 
lower risk of head and neck cancers than people who don't smoke 
marijuana. Alas, this important research has been largely ignored by 
the news media.

While this type of study cannot conclusively prove cause and effect, 
the combination of this new study and existing research -- which for 
decades has shown that cannabinoids are fairly potent anticancer 
drugs -- raises a significant possibility that marijuana use is in 
fact protective against certain types of cancer.

A team of researchers from several major universities conducted what 
is known as a "case-control" study, comparing patients who had 
squamous cell carcinoma of the mouth, larynx, and pharynx with 
control patients matched for age, gender, and residence location who 
did not have cancer. By looking at matched groups with and without 
cancer, researchers hope to find patterns indicating risk or 
protective factors. In this case they focused on marijuana use, but 
also took into account known risk factors for this type of cancer, 
including tobacco and alcohol use.

After adjusting for those confounding factors, current marijuana 
users had a 48% reduced risk of head and neck cancer, and the 
reduction was statistically significant. Former users also had a 
lower risk, though it fell short of being significant. The 
investigators crunched the numbers several different ways -- for 
example, by amount of marijuana used or the frequency of use -- and 
the findings stayed the same nearly across the board, with moderate 
users showing the strongest and most consistent reduction in cancer risk.

The scientists write, "We found that moderate marijuana use was 
significantly associated with reduced risk HNSCC [head and neck 
squamous cell carcinoma]. The association was consistent across 
different measures of marijuana use (marijuana use status, duration, 
and frequency of use)."

Strikingly, among drinkers and cigarette smokers, those who also used 
marijuana reduced their cancer risk compared to those who only drank 
and smoked cigarettes. So marijuana may actually have been countering 
the known bad effects of booze and cigarettes.