RandyW Posted July 15, 2006 Share Posted July 15, 2006 Smoking pot may prime lungs for cancer Reuters Friday, 14 July 2006 The researchers could not directly link smoking marijuana with lung cancer. But they found evidence of precancerous changes in the lung like oxidative stress, damaged tumour-fighting cells, and DNA and tissue changes (Image: iStockphoto) Smoking marijuana can cause changes in lung tissue that may promote cancer, according to a review of decades of research on marijuana smoking and lung cancer. Still, it is not possible to directly link pot use to lung cancer based on existing evidence. Dr Reena Mehra of Case Western Reserve University in Cleveland, Ohio and her colleagues publish their review in the current issue of the Archives of Internal Medicine. "Given the widespread use of marijuana, its use for what are believed to be medicinal purposes, and the increasing abuse and dependence on this substance, it is important to examine potential adverse clinical consequences," the researchers write. To investigate whether marijuana smoking might lead to precancerous changes in the lungs or lung cancer, Mehra and her team reviewed 19 studies. Analyses of sputum and lung tissue performed in some of these studies found more cancer-promoting changes in pot smokers than in cigarette smokers or non-smokers. These changes included oxidative stress, dysfunction of tumour-fighting cells, changes in tissue structure and DNA alterations, the researchers report. But none of the studies they analysed found evidence that marijuana smoking actually caused lung cancer, after factoring in the effects of tobacco use. "We must conclude that no convincing evidence exists for an association between marijuana smoking and lung cancer based on existing data," Mehra and her team write. Increased risk Nevertheless, the researchers add, the precancerous changes seen in studies included in their analysis and other factors do suggest that smoking pot could indeed boost lung cancer risk. Other factors that could make pot smokers prone to lung cancer, the researchers say, include the fact that they generally inhale more deeply and hold smoke in their lungs longer than cigarette smokers, and that marijuana is smoked without a filter. It is known, they add, that marijuana smoking deposits more tar in the lungs than cigarette smoking does. The failure to find a marijuana-lung cancer link may have been due to methodological flaws in existing research, rather than the absence of such a link, the researchers say. Doctors should advise their patients that marijuana does indeed have potential adverse effects, they conclude, including causing precancerous changes in the lungs. For more information about drugs and their side-effects, see the DrugInfo Clearing House website run by the Australian Drug Foundation. Related Stories Cannabis-like drugs may help bowel disease, News in Science 15 Aug 2005 Stoned sperm too speedy to fertilise, News in Science 14 Oct 2003 How marijuana makes you vague, News in Science 30 Mar 2001 Quote Link to comment Share on other sites More sharing options...
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