Marijuana Unlikely to Cause Head, Neck, or Lung Cancer
"We attempted to assess both lifetime and current use of substances," he says. Participants were also asked to differentiate between use of marijuana cigarettes, marijuana pipes, or consumed marijuana. Distinctions were also made between weekend and weekday use of marijuana, he says.
"Ever use of marijuana was 66% among controls and 60% among the cases," he says. "Daily marijuana use for a month or more was not associated with increased risk, nor was age at first use, depth of inhalation, or use of a pipe." Surprisingly, using marijuana was not associated with increased cancer risk, even among those who never used tobacco, he says.
During the discussion period after the presentation, several people suggested that lack of quantity may explain why no association was found, because the number of marijuana cigarettes smoked is much lower than the number of tobacco cigarettes smoked. "It is true that we can't really correlate pack-years," says Ford, "and it should be noted that about 30% of the marijuana smokers never smoke cigarettes."
While this study suggests that marijuana has no link to head, neck, and lung cancer, a multicenter study released in March at an American Heart Association meeting linked marijuana use to increased risk of heart attacks. Murray A. Mittleman, MD, PhD, director of cardiovascular epidemiology at Beth Israel-Deaconess Hospital in Boston, told WebMD that marijuana smokers experience a 4.8-fold increase in the relative risk of heart attack during the first hour after smoking. The risk returns to normal after an hour, he said.
- New research shows that marijuana use is not associated with an increased risk of head, neck, or lung cancers.
- One researcher argues that cancer prevention efforts should remain focused on tobacco and alcohol, both known carcinogens.
- Although there is no evidence that marijuana smoking increases the risk of cancer, studies have shown that marijuana smokers have a nearly five-fold increased risk of having a heart attack during the first hour after smoking.