Cannabinoids,
constituents of marijuana smoke, have been recognized to have potential
antitumor properties. A study by Liang and colleagues from Brown University, Providence, RI, found that
long-term marijuana smokers were roughly 62 % less likely to develop head and
neck cancers than people who did not smoke pot.
The
study featured 434 patients with head and neck cancers, which include tumors in
the mouth, tongue, nose, sinuses, throat and lymph nodes in the neck, and 547
individuals without these cancers seen in the Greater Boston area from 1999 to 2003. 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 even in those who smoked or consumed
alcohol. Among marijuana users moderate weekly use was associated with reduced risk.
The magnitude of reduced risk was more pronounced for those who started use at
an older age.
In
contrast a pooled analysis from nine case-control studies from the US and Latin
America by Marks and colleges, found that as compared with never marijuana smokers, ever marijuana smokers had an elevated risk of oropharyngeal and a
reduced risk of oral tongue cancer. Evaluated were 1,921 oropharyngeal cases,
356 oral tongue cases, and 7,639 controls. The risk of oropharyngeal cancer remained elevated among
never tobacco and alcohol users. The risk of oral tongue cancer was reduced
among never users of tobacco and alcohol. These results suggest that the
association of marijuana use with head and neck carcinoma may differ by tumor
site.
Marijuana leaves