For some 35 years the United States federal government has been well aware that cannabis possesses potent anti-cancer and anti-tumor properties. And for the past three years, government-funded researchers have speculated that these qualities may offer “protective” effects against the onset of various types of cancer in humans, including lung cancer.

Yet to date, virtually no investigators have taken the time to assess marijuana’s potential anti-cancer effects in humans — until now.

In a clinical abstract just published online on the Cancer Prevention Research website, a team of U.S. investigators report that marijuana use, even long-term, is associated with a “significantly reduced risk” of head and neck squamous cell carcinoma.

A Population-Based Case-Control Study of Marijuana Use and Head and Neck Squamous Cell Carcinoma

Cannabinoids, constituents of marijuana smoke, have been recognized to have potential anti-tumor properties. However, the epidemiologic evidence addressing the relationship between marijuana use and the induction of head and neck squamous cell carcinoma (HNSCC) is inconsistent and conflicting. Cases (n = 434) were patients with incident HNSCC disease from nine medical facilities in the Greater Boston, MA area between December 1999 and December 2003. Controls (n = 547) were frequency matched to cases on age (+/-3 years), gender, and town of residence, randomly selected from Massachusetts town books.

…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 HNSCC [odds ratio (OR)(10-<20 years versus never users), 0.38; 95% confidence interval (CI), 0.22-0.67]. Among marijuana users moderate weekly use was associated with reduced risk (OR(0.5-<1.5 times versus <0.5 time), 0.52; 95% CI, 0.32-0.85). The magnitude of reduced risk was more pronounced for those who started use at an older age (OR(15-<20 years versus never users), 0.53; 95% CI, 0.30-0.95; OR(>/=20 years versus never users), 0.39; 95% CI, 0.17-0.90; P(trend) < 0.001).

Our study suggests that moderate marijuana use is associated with reduced risk of HNSCC.

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