A new research review concludes that smokeless-tobacco use poses little cancer risk to users -- and far less than smoking tobacco -- but the findings were immediately challenged by another tobacco researcher.

MedPage Today reported July 29 that researchers Peter Lee and Jan Hamling analyzed 89 previously published studies and concluded, "Any effect of smokeless tobacco on risk of cancer, if it exists at all, is quantitatively very much smaller than the known effects of smoking."

The authors, both of PN Lee Statistics and Computing, said that smokeless tobacco use only appears related to oropharyngeal and prostate cancer, with risk increasing by 36 percent and 29 percent, respectively. But Lee and Hamling even cast doubt on these data.

The U.S. National Cancer Institute, however, says that chewing tobacco and snuff contain 28 known carcinogens, and critics pointed out that Lee is a consultant to the tobacco industry. University of Florida researcher Scott Tomar said that no serious researcher would argue that smokeless-tobacco use is as harmful as smoking, and questioned the methodology and conclusions drawn by Lee and Hamling.

The study was published in the journal BMC Medicine.