Wednesday, March 30, 2011

More Misinformation About Smokeless Tobacco From the American Cancer Society

American Cancer Society (ACS) investigators have just published results of a study on alcohol consumption and the development of pancreas cancer in the Archives of Internal Medicine (abstract here). Led by Susan M. Gapstur, the study found that, compared with never alcohol drinkers, consumers of three or more drinks per day had an elevated risk of pancreas cancer mortality. The higher risk was statistically significant for never smokers (Relative risk, RR = 1.36, 95% Confidence Interval, CI = 1.13 – 1.62) and for ever smokers (RR = 1.16, CI = 1.06 – 1.27). They did not detect higher risks for beer or wine drinkers, but only for consumption of liquor.

The article discussed the public health implications of the research:

“Alcoholic beverage consumption—a modifiable lifestyle factor—is causally related to several cancers, including oral cavity, pharynx, larynx, esophagus, liver, colorectum, and female breast. Findings from the prospective study presented herein strongly support the hypothesis that alcohol consumption, in particular heavy intake, also is an independent risk factor for pancreatic cancer, the fourth most common cause of cancer mortality in the United States. These results underscore the importance of adhering to the following guideline for cancer prevention by the American Cancer Society: ‘If you drink alcoholic beverages, limit consumption.’”

Thus, while the ACS acknowledges that alcohol is associated with considerable cancer risks, its advice to consumers emphasizes moderation. Historically, moderation has played no role in ACS messages to tobacco users: quit now and abstain completely and permanently.

The ACS web page on smokeless tobacco (available here) was revised on December 16, 2010; it is replete with misinformation, especially about cancer risks. Following are the cancers that the ACS claims, with no supporting data, are caused by smokeless tobacco use, followed by the actual scientific evidence derived from the most comprehensive study ever published (read about it here).

American Cancer Society ClaimActual Scientific Evidence
Mouth, tongue and throat cancer Not significantly elevated, RR = 1.07 (CI = 0.84-1.37)
Esophagus cancer Not significantly elevated, RR = 1.13 (CI = 0.95-1.36)
Stomach cancer Not significantly elevated, RR = 1.03 (CI = 0.88-1.20)
Pancreatic Cancer Not significantly elevated, RR = 1.07 (CI = 0.71-1.60)
RR = Relative Risk.

Scientific evidence shows clearly that smokeless tobacco use only slightly elevates cancer risks, if at all. The reported elevations are so small that they are not statistically significant; in other words, they may have occurred purely by chance. It is also important to point out that small RRs (those under 2) should not be seen as reliable. The National Cancer Institute advises: “Relative risks or odds ratios less than 2 are viewed with caution,” because they “are sometimes difficult to interpret.”

Next week I will discuss ACS intransigence with respect to refusing to provide information in its possession about the health risks related to tobacco use.

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