“Marijuana (Cannabis sativa) contains more than 60 unique compounds known as cannabinoids. Cannabinoids, constituents of marijuana smoke, have been recognized to have potential antitumor properties. However, the epidemiological evidence addressing the relationship between marijuana use and the induction of head and neck cancer (HNSCC) is inconsistent and conflicting. An early epidemiological study reported that marijuana use was associated with an elevated risk for head and neck cancer.  However, more recent studies have failed to confirm the association of marijuana use with an increased head and neck cancer risk.

 In fact, many of these studies reported non-significant protective estimates of effect, consistent with a possible anticarcinogenic action of cannabinoids.

A recent epidemiologic review raised the need for additional, well conducted, large studies to clarify the nature of the association of marijuana use with the risk of cancer, especially head and neck cancer. In order to further elucidate the association between marijuana use and head neck cancer risk, we assessed marijuana use in detail in a population-based case-control study.

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.

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