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The study was conducted by Annah Wyss of the National Institute of Environment Health Science and 20 government-funded coauthors, and the results suggested that while amongst men there were no cases of mouth cancer associated with dipping or chewing tobacco, amongst women who mainly used powdered dry snuff, the chance of contracting this kind of cancer was 9 times as much higher.

A letter demanding further required details

Member of the James Graham Brown Cancer Center, tobacco harm reduction research expert, and Professor of medicine at the University of Louisville Brad Rodu, wrote a letter to the editors in which he explained why the study was inaccurate and did not contain enough information:

“In the article… Wyss et al. omit key information that would likely yield critical insights about their most important result.

“Wyss et al. reported that ever use of snuff among never cigarette smokers was associated with head and neck cancer (OR = 1.71, [95% Confidence Interval] CI: 1.08, 2.70), based on 44 exposed cases and 62 exposed controls.  The OR among women ever snuff users (8.89, CI: 3.59, 22.0, based on 20 exposed cases and 12 controls) was an order of magnitude higher than that in men (0.86, CI: 0.49, 1.51, based on 24 exposed cases and 50 controls).

“The striking difference between women and men reflects completely different snuff exposures.  It is widely known that in the southern U.S. women primarily use powdered dry snuff, whereas men throughout the U.S. use moist snuff.  Powdered dry snuff use is associated with excess oral cancer risk in four previous studies (Reference 2), all of which were cited by Wyss (3, 4, 5, 6).  In contrast, moist snuff is associated with minimal to no risk in eight previous studies (2).

“Wyss and colleagues are knowledgeable about the use of powdered dry snuff by women and its cancer risk; one was first author of a 1981 study reporting that “[t]he relative risk [for oral and pharyngeal cancer] associated with snuff dipping among white [women] nonsmokers [in North Carolina] was 4.2 (95 per cent confidence limits, 2.6 to 6.7).” (4) Subjects in that study had exclusively used powdered dry snuff.  

“Wyss et al. used pooled data from 11 US case-control studies located throughout the U.S.  They have information to confirm that the 20 female [powdered dry] snuff users with cancer were from study sites in the Southern U.S., whereas the 24 male [moist] snuff users were from more diverse locations.  This information is not available from the 12 publications cited by Wyss et al. as data sources.  Six publications had insufficient information about exposed and unexposed cases and controls (i.e. no specificity with respect to smokeless tobacco type, gender, and/or smoking), three reported no results related to any smokeless tobacco product and three did not mention smokeless tobacco at all.

“Wyss et al. should provide in tabular form the number of exposed and unexposed cases and controls separately for never smoking men and women from each of the 11 source studies.  This information is routinely provided in publications of pooled analyses, and it is available in the existing data and results files.”

More misinterpreted data

Since the 80’s there have been several studies indicating that the huge difference in mouth cancer risk between women and men is basically attributable to the fact that they they consume powdered dry snuff instead of moist snuff.
Dr. Wyss and her coauthors replied to Professor Rodu with the requested additional results, and while they confirmed that no risks were observed among men who dip, Rodu pointed out that their conclusion related to risks amongst women were inaccurate. “Snuff use was strongly associated with elevated [head and neck cancer] risk in both Southern women…and non-Southern women,” read the researchers’ reply.

In a blog published last week, Professor Rodu explained why this statement is inaccurate. “In Southern women, the risk was quite high (OR = 11.25) and statistically significant, but with a wide 95% confidence interval (2.14 – 59.07), owing to the fact that the OR was based on only 26 cases.  In non-Southern women, the OR was even higher, at 15.91, but this was based on a mere 6 cases. While statistically significant from a technical perspective (CI = 1.20 – 211.43), the CI is so large and unstable that the estimate is virtually meaningless.”

The professor pointed out that Dr. Deborah Winn of the National Cancer Institute, who co authored this study is aware that powdered dry snuff is the only smokeless product that carries mouth cancer risk, yet her only comment in this latest report was, “we cannot comment on whether snuff users – female or male, Southern or non-Southern – in our analysis used dry or moist snuff.

“In Southern women, the risk was quite high (OR = 11.25) and statistically significant, but with a wide 95% confidence interval (2.14 – 59.07), owing to the fact that the OR was based on only 26 cases.  In non-Southern women, the OR was even higher, at 15.91, but this was based on a mere 6 cases. While statistically significant from a technical perspective (CI = 1.20 – 211.43), the CI is so large and unstable that the estimate is virtually meaningless.”Professor Brad Rody, University of Louisville

Government-funded studies keep misreporting pre-established facts

Brad Rodu concluded by pointing out that since the 80’s there have been several studies indicating that the huge difference in mouth cancer risk between women and men is basically attributable to the fact that they they consume powdered dry snuff instead of moist snuff. Despite this, government-funded researchers keep stating misinterpreted facts and hence misinformation, leading the public to believe that all smokeless tobacco products are dangerous.

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