The risk of oral cancer jumped 90 percent in women and 60 percent in men who gargled daily for decades using a mouthwash with a high alcoholic content, federal researchers report. A published paper in the journal Cancer Research provided details to an earlier report about the mouthwash study, conducted by investigators at the National Cancer Institute.
Word of the study had leaked out after one of the authors, Dr. William Blot, outlined its results at a cancer conference in Atlanta. The flurry of news media attention shook the dental hygiene industry, not surprisingly because more than a third of U.S. adults say they use mouthwash.
The paper, however, makes clear that the heightened oral cancer risk applied only to mouthwashes with greater than a 25 percent alcohol content. Currently, only Listerine exceeds that proportion. Warner-Lambert has announced plans to market a lower-alcohol version of Listerine.
Users of mouthwashes with less than 25 percent alcohol showed no increased risk of oral cancer. Those who used any mouthwash regularly for fewer than 20 years also did not appear to be at greater risk.
Blot emphasized that despite the new study, conducted among a sample of 866 people with oral cancers and 1,249 without, smoking and alcohol consumption are the "two greatest and best established risk factors for the disease."
A lifetime of both smoking and drinking can multiply oral cancer risk by as many as 35 times, Blot said. Chewing tobacco is another recently recognized risk factor in the cancer.
Joseph McLaughlin, another NCI investigator and study author, called mouthwash "a minor player in this drama." The researchers said it was too early to make any recommendations to mouthwash users about the risk of oral cancer and added they were continuing research on all potential risk factors for the disease.