Marijuana Unlikely to Cause Head, Neck, or Lung Cancer
May 8, 2000 (Boston) -- Marijuana, unlike tobacco and alcohol, does not appear to cause head, neck, or lung cancer, says a researcher from Johns Hopkins Medical School in Baltimore who presented findings from a study here recently at a meeting of internal medicine physicians.
There has been an ongoing debate about whether marijuana is as dangerous as tobacco in terms of cancer development. Daniel E. Ford, MD, tried to sort out the evidence by the lifestyles -- including marijuana, tobacco, and alcohol use -- of 164 persons who were newly diagnosed with head, neck, or lung cancer compared to a group of 526 healthy persons living in the same area. The average age of patients was 49, while the average age of the healthy volunteers was 44. The cancer patients were all treated at four Baltimore-area hospitals, and the "controls" (healthy comparison group) were selected from a large group of people living in the Baltimore area who had been participating in an ongoing study. Ford tells WebMD that he wanted to find out whether the cancer patients were more likely to smoke marijuana or tobacco or to drink than were the healthy volunteers.
According to Ford, he thought he would find an association between marijuana use and cancer, but "that the association would fall away when we corrected for tobacco use. That was not the case. The association was never there." And that surprised him because of the way marijuana is smoked: deep inhalations, with the smoke held in for effect. "It seemed natural that there would be some connection," he tells WebMD.
Based on these findings, Ford says that cancer prevention efforts should "remain focused on tobacco and alcohol, two known carcinogens."
He says his conclusions differ from another study reported recently. That study linked marijuana use to cancer, but Ford says he thinks the difference can be explained by the fact that the healthy volunteers in that study "had very, very low use of marijuana." That contrasts to his study, in which "we were investigating the effect of marijuana as it is commonly used in the community," he says. Use of all substances -- tobacco, alcohol, and marijuana -- was common among both cancer patients and controls, he says.