THURSDAY, July 3 (HealthDay News) -- Smokeless tobacco users probably have a lower risk of several common cancers than smokers, but a higher risk than people who use no tobacco products, according to the results of a study published in the July issue of The Lancet Oncology.
Paolo Boffetta, M.D., of the International Agency for Research on Cancer in Lyon, France, and colleagues conducted an extensive database search for relevant reports published in any language between October 2004 and September 2007. Most of the studies were conducted in the United States, northern Europe and India.
The researchers found that cancer risk varied by region. Although data from the United States and Asia showed an association between smokeless tobacco and the risk of oral cancer (relative risk, 2.6), data from northern European studies showed no increased risk. However, data from northern Europe did show an association between smokeless tobacco and a risk of esophageal and pancreatic cancer (relative risk, 1.6 for each). They also found that data on lung cancer have been inconsistent, noting that northern European studies showed no increased risk. Smokeless tobacco accounts for more than 50 percent of oral cancers in India and Sudan compared to 4 percent in the United States, and also accounts for 20 percent of esophageal and pancreatic cancers in Swedish men, according to the researchers.
"Several conclusions can be reached based on the available data: use of smokeless tobacco products is widespread in many populations, but their health effects (especially with respect to cancer risk) need to be better characterized; such use results in exposure to carcinogens, notably nitrosamines; the risk of cancer depends on the type of product consumed, and the concentration of nitrosamines is the strongest factor to determine product-specific risk," the authors write.
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