Pot Smoking Not Linked to Lung Cancer
Study Shows No Increased Risk for Even the Heaviest Marijuana Smokers
WebMD News Archive
The THC Connection
Studies suggest that marijuana smoke contains 50% higher concentrations of chemicals linked to lung cancerlung cancer than cigarette smoke. Marijuana smokers also tend to inhale deeper than cigarette smokers and hold the inhaled smoke in their lungs longer.
So why isn’t smoking marijuana as dangerous as smoking cigarettes in terms of cancercancer risk?
The answer isn’t clear, but the experts say it might have something to do with tetrahydrocannabinol, or THC, which is a chemical found in marijuana smoke.
Cellular studies and even some studies in animal models suggest that THC has antitumor properties, either by encouraging the death of genetically damaged cells that can become cancerous or by restricting the development of the blood supply that feeds tumors, Tashkin tells WebMD.
In a review of the research published last fall, University of Colorado molecular biologist Robert Melamede, PhD, concluded that the THC in cannabis seems to lessen the tumor-promoting properties of marijuana smoke.
The nicotine in tobacco has been shown to inhibit the destruction of cancer-causing cells, Melamede tells WebMD. THC does not appear to do this and may even do the opposite.
While there was a suggestion in the newly reported study that smoking marijuana is weakly protective against lung cancer, Tashkin says the very weak association was probably due to chance.
Cancer risk among cigarette smokers was not influenced by whether or not they also smoked marijuana.
“We saw no interaction between marijuana and tobacco, and we certainly would not recommend that people smoke marijuana to protect themselves against cancer,” he says.