For 35 years the federal government has been well aware — yet publicly denied — that cannabis possesses potent anti-cancer and anti-tumor properties. Even under the Obama administration, which promised to "base [their] public policies on the soundest of science," the myth that pot promotes cancer persists. In fact, the White House’s website, whitehousedrugpolicy.gov, presently warns, "Marijuana has the potential to promote cancer of the lungs and other parts of the respiratory tract."

Or not.

In a clinical abstract published online on journal of Cancer Prevention Research website in July, a team of U.S. investigators reported — with absolutely no mainstream media fanfare — that lifetime marijuana use is associated with a "significantly reduced risk" of head and neck squamous cell carcinoma.

Investigators at Rhode Island’s Brown University, along with researchers at Boston University, Louisiana State University, and the University of Minnesota assessed the lifetime marijuana use habits of 434 cases (patients diagnosed with head and neck squamous cell carcinoma from nine medical facilities) compared to 547 matched controls.

Authors reported, "After adjusting for potential confounders (including smoking and alcohol drinking), 10 to 20 years of marijuana use was associated with a significantly reduced risk of head and neck squamous cell carcinoma (HNDCC).”

Perhaps even more notably, subjects who smoked marijuana and consumed alcohol and tobacco (two known high-risk factors for head and neck cancers) also experienced a reduced risk of cancer, the study found.

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"Our study suggests that moderate marijuana use is associated with reduced risk of HNSCC," investigators concluded. "This association was consistent across different measures of marijuana use (marijuana use status, duration, and frequency of use). … Further, we observed that marijuana use modified the interaction between alcohol and cigarette smoking, resulting in a decreased HNSCC risk among moderate smokers and light drinkers, and attenuated risk among the heaviest smokers and drinkers."

Of course, this isn’t the first time that U.S. investigators have documented an inverse association between pot use and cancer. A separate 2006 population case-control study, funded by the U.S. National Institutes of Health and conducted by the University of California at Los Angeles, also reported that lifetime use of cannabis was not positively associated with cancers of the lung or aerodigestive tract, and further noted that certain moderate users of the drug experienced a reduced cancer risk compared to non-using controls.

Predictably, the federal government’s goal when green-lighting the UCLA study was to conclusively establish just the opposite result, as explained recently by its lead researcher Dr. Donald Tashkin.

In an interview with the McClatchy newspaper chain in June, Tashkin admitted that he expected his study would find that pot was associated with "increased health effects." Instead, he summarized, "What we found instead was no association (between marijuana smoking and cancer) and even a suggestion of some protective effect."

Perhaps that explains why Tashkin’s study, the largest trial of its kind, is inexplicably absent from the White House’s website.

Tashkin added, "[A]t this point, I’d be in favor of (marijuana) legalization. I wouldn’t encourage anybody to smoke any substances. But I don’t think it should be stigmatized as an illegal substance. Tobacco smoking causes far more harm. And in terms of an intoxicant, alcohol causes far more harm (than marijuana)."

Indeed it does. In fact, according to the findings of a study published online August 3 in the journal Cancer Epidemiology, even moderate alcohol consumption (defined as six drinks or less per week) is positively associated with an elevated risk of various cancers — including stomach cancer, rectal cancer, and bladder cancer. The study is the second to be published this year indicating that those who consume even minor amounts of booze are at increased risk for cancer. In February, a British study of some 1.3 million women age 50 to 64 reported that imbibing in as little as one alcoholic beverage per day significantly elevated females’ risk of cancer, particularly breast cancer.

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For those of us who have closely studied the physiological effects of pot and alcohol the two substances contrasting association with cancer isn’t surprising. Ethanol, the psychoactive ingredient in booze, is converted by the body to acetaldehyde, a known carcinogen. By contrast, the active components in marijuana — known as cannabinoids — are relatively non-toxic and actually mimic chemicals naturally produced by the body (so-called endocannabinoids) that are necessary for maintaining one’s proper health.

Of course, that’s hardly where the differences between marijuana and alcohol end. As I write in my new book Marijuana Is Safer: So Why Are We Driving People to Drink (Chelsea Green Publishing, 2009), alcohol consumption is toxic to cells and healthy organs, can depress the central nervous system (inducing unconsciousness, coma, and death), and is strongly associated with increased risks of injury and acts of violence. The use of marijuana, on the other hand, is incapable of causing fatal overdose — cannabinoids do not act upon the brain stem — and its use is inversely associated with aggression and injury.

Naturally, none of these differences should imply that America should return to the days of alcohol prohibition. Rather, they should spark a long-overdue dialogue in this country asking why our laws target and prosecute those adults who choose to make the rational choice to relax with a substance that is objectively safer, both to the user and to society as a whole, than alcohol. Perhaps when the President finishes his beer, he can provide an answer.

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