Lyon, France: Moderate use of cannabis not does appear to be associated with an increased risk of tobacco-related cancers, such as lung or colorectal cancer, according to an epidemiological review published in the current issue of the journal Alcohol.
Following the review of two cohort studies and 14 case-control studies, authors concluded, "Results of cohort studies have not revealed an increased risk of tobacco-related cancers among marijuana smokers, possibly because few users smoke enough marijuana to elevate their risk to a detectable level."
Authors did acknowledge an increased risk of certain cancers in a handful of case-control studies, but noted that the results were inconsistent, "highly unstable," and may reflect researchers having controlled poorly for other drug use, including tobacco and alcohol.
A 1999 review by the National Academy of Sciences Institute of Medicine found "no conclusive evidence that marijuana causes cancer in humans, including cancers usually related to tobacco use."
For more information, please contact Paul Armentano, NORML Senior policy Analyst, at (202) 483-5500. Full text of the study, "Epidemiological review of marijuana use and cancer risk," is available in the August issue of the journal Alcohol.