A Smokeless Tobacco-Pancreatic Cancer Claim is Refuted

Snus use is not associated with pancreatic cancer, according to a study published in the International Journal of Cancer (abstract here).  Researchers combined data from nine cohort studies that involved 400,000 men in Sweden.  Compared with never users, the risk for current snus users, after adjustment for smoking, was 0.96 (95% confidence interval = 0.83 – 1.11).

The new work was conducted by the Swedish Collaboration on Health Effects of Snus Use, which includes researchers from several Swedish universities.  (In the past, snus research was largely performed by the Karolinska Institute, whose flawed studies I have previously documented here, here, here, and here.)  Their results are almost identical to those in a large study of smokeless use in North America and Europe published six years ago (discussed here), and to findings in another analysis published eight years ago (here).

Focus on a purported smokeless tobacco-pancreatic cancer link began after publication of a cherry-picked meta-analysis by Paolo Boffetta in 2008 (discussed here).  Dr. Boffetta contradicted his own finding in a later study (here), and epidemiologist Peter Lee refuted it in his comprehensive analysis in 2009 (here).  The fact is that there is no credible evidence that American or Swedish smokeless tobacco is linked to pancreatic cancer.      

Remarkably, the National Cancer Institute persists in asserting a pancreatic cancer link in its smokeless tobacco “fact sheet” (here).  That document also asks what should be a rhetorical question: “Is using smokeless tobacco less hazardous than smoking cigarettes?” 

The NCI’s answer is grossly misleading: “all tobacco products are harmful and cause cancer…There is no safe level of tobacco use.”  The agency’s source for this obfuscation is a 31-year-old Surgeon General report that has been eclipsed by three decades of epidemiologic studies.  

It should be noted that the U.S. Food & Drug Administration is equally culpable. That agency used the bogus smokeless-pancreatic cancer link as a talking point in last year’s $36 million campaign against smokeless tobacco (here).

We already knew that moist snuff and chewing tobacco have no measurable risk for mouth cancer (here).  Now there is scientific evidence that smokeless isn’t linked to pancreatic cancer.   

Heavy Snus Use: Possible Link to Type 2 Diabetes

A Swedish research study finds that heavy consumption of snus is associated with type 2 diabetes (abstract here). 

Analyzing data from six groups of Swedish men, researchers found no risk of type 2 diabetes in all snus users combined, but they reported a modest elevated risk with higher levels of consumption, at 5-6 cans per week (Relative risk, RR = 1.42, 95% Confidence Interval, CI = 1.07 – 1.87) or 7+ cans per week (RR = 1.68, CI = 1.17 – 2.41).

In a Karolinska Institute press release (here), lead research author Sofia Carlsson said, “We can confirm earlier suspicions that snus-users have a higher risk of type 2 diabetes.”  In fact, the new study confirmed only one “earlier suspicion”, as Carlsson’s is only the second study to show an association at higher consumption levels.  Here are the results from the four studies that have been published to date:

Studies of Snus Use and Type 2 Diabetes in Sweden
Author, Year, Snus Users	Relative Risk (95% CI)
Eliasson et al., 2004
Current snus users (prevalent diabetes)	1.06 (0.43 – 2.64)
Current snus users (follow-up diabetes)	No cases
Ӧstenson et al., 2012
Current snus users	1.1 (0.6 – 2.0)
1-5 cans per week	0.6 (0.2 – 1.4)
6+ cans per week	3.3 (1.4 – 8.1)
Rasouli et al., 2017
A. Current snus users	0.96 (0.67 – 1.37)
A. Ever snus users
Less than 5 boxes per week	0.78 (0.56 – 1.09)
5+ boxes per week	0.95 (0.57 – 1.58)
B. Ever snus users	0.91 (0.75 – 1.10)
Less than 3 boxes per week	0.88 (0.72 – 1.08)
3 + boxes per week	0.92 (0.46 – 1.83)
Carlsson et al., 2017
Current snus users	1.15 (1.00 – 1.32)
1-2 boxes per week	1.14 (0.86 – 1.50)
3-4 boxes per week	1.03 (0.82 – 1.29)
5-6 boxes per week	1.42 (1.07 – 1.87)
7+ boxes per week	1.68 (1.17 – 2.41)

A.    Swedish snus users

B.    Norwegian snus users

    Significantly elevated RRs

While those two studies suggest that high snus consumption is associated with type 2 diabetes, more research is needed to confirm a link. Many other factors are known to contribute to this type of diabetes (here), including age, overweight or obesity, inactive lifestyle, smoking (here), family history, high blood pressure and high blood cholesterol levels.  Research and analysis must fully account for these factors in order to confirm or refute a snus link.

Up in Vapor: The Real Story Behind the Formaldehyde-Cancer Link

Vapers, rest easy about e-cigarettes and formaldehyde. 

As a pathologist with 28 years’ formaldehyde exposure via workplace inhalation, I have both a professional and a personal interest in whether formaldehyde causes cancer.  It turns out that the formaldehyde-cancer link is weak to nonexistent, and it has been grossly exaggerated by organizations like the International Agency for Research on Cancer (IARC) and the U.S. National Toxicology Program (NTP).  In many ways, formaldehyde has been treated much like smokeless tobacco, which the same agencies list as a carcinogen in spite of weak to nonexistent epidemiologic evidence (here).    

The fact is, IARC and NTP primarily base their formaldehyde carcinogen classification on a single National Cancer Institute (NCI) study claiming that the agent causes nasopharyngeal cancer, or NPC.  That study, published in 2004 by NCI’s Michael Hauptmann and colleagues, has been shown to be unreliable.

The Hauptmann study was based on 25,000 workers, most of whom were exposed to formaldehyde at 10 industrial plants over a 30-year period.  Compared with unexposed workers, Hauptmann et al. reported that formaldehyde-exposed workers had about a two-fold higher risk for NPC, based on eight cases.  No other increased cancer risks were observed.   

The Hauptmann data was reassessed in 2005 by Gary Marsh, Ph.D., a University of Pittsburgh statistician who was supported by the Formaldehyde Council, an industry group. 

Dr. Marsh reported (abstract here) that “reanalysis provided little evidence to support NCI’s suggestion of a causal association between formaldehyde exposure and mortality from NPC.”  He pointed out that Hauptmann had based his conclusion on an excess of NPC in only one plant, located in Wallingford, Connecticut.  In the other nine plants, formaldehyde-exposed workers had lower-than-expected NPC rates.

Dr. Marsh continued to investigate the NPC cancers at Wallingford.  In 2007, he published another study showing that the NPC excess at the Wallingford factory was probably not due to formaldehyde, but to workers’ exposure “to several suspected risk factors for upper respiratory system cancer (e.g., sulfuric acid mists, mineral acid, metal dusts and heat).”

The NCI team had also claimed that the highest exposures to formaldehyde resulted in the highest NPC risks.  Dr. Marsh showed that claim to be wrong in a third study published in 2007 (here).     

In 2010, Annette Bachand and colleagues conducted a comprehensive meta-analysis, which included “all relevant cohort and case-control studies published through May 2009.”  They found no overall increase in NPC risk after excluding Hauptmann’s Wallingford plant data.  Six case control studies produced a marginally elevated risk for NPC among formaldehyde-exposed workers (OR = 1.22, 95% Confidence Interval = 1.00 – 1.50), which may have been due to a failure to adjust for smoking, a known risk factor for NPC.  Seven cohort studies resulted in a lower NPC risk among exposed workers (OR = 0.72, CI = 0.40 – 1.29). Bachand’s results were in agreement with an earlier meta-analysis by Bosetti et al.

Inflated claims by NCI epidemiologists are not unprecedented; witness the 1981 assertion by Dr. Deborah Winn that all American smokeless tobacco users were at risk for mouth cancer (completely refuted here and here).

The only bright side of this story is that the NCI formaldehyde-cancer claim could be analyzed because the agency’s data was available to outside investigators.  In contrast, the Karolinska Institute and the American Cancer Society have issued warnings about smokeless tobacco but persist in withholding the underlying data (here and here) – a violation of data-sharing and research practice standards. 

Swedish Tax Proposal Threatens Successful Tobacco Harm Reduction

Sweden, which represents the world’s best example of the population effect of tobacco harm reduction, is considering increasing its snus tax by 22%, according to the Swedish national newspaper Aftonbladet.  An April 2 article claims “it would be the first time ever that a can of snus would cost more than a pack of cigarettes.”  Swedes are reportedly outraged by the proposal.  Public health experts should be outraged as well, given such a tax hike’s threat to the developed world’s lowest smoking and lung cancer rates.

As expected, the Karolinska Institute’s tobacco expert Hans Giljam expressed support for a higher snus tax.  However, even he admitted, “There is a risk that many will quit snus and move to cigarettes.  And if many start smoking instead of using snus, we will get sicker. That is a certainty.”

That is unquestionably the strangest endorsement of tobacco harm reduction ever heard.  Giljam couched his comment in dire, unfounded or exaggerated warnings about links between snus and a host of diseases, but he waffled on how much snus use triggers health effects.  “It takes decades of study to reach such conclusions.  It is one of the pedagogic problems we face; we don’t really know what the health effects of long-term snus usage are.”

In fact, decades of study have defined the long-term health effects snus use – nearly zero.  And even Giljam acknowledges that smoking is at least ten times more dangerous than using snus.  His support for equalizing taxes on snus and cigarettes is unfathomable.

This article is available only in Swedish (here), so the English translation I have could account for Giljam’s bizarre logic.  But I sincerely doubt it.  Like anti-tobacco extremists everywhere, those in Sweden not only completely ignore the phenomenal Swedish tobacco experience, they enthusiastically endorse policies that would destroy it.