Systematic review of the relation between smokeless tobacco and cancer of the pancreas in Europe and North America

Abstract

BackgroundRecent reviews claiming smokeless tobacco increases pancreatic cancer risk appear not to have considered all available epidemiological evidence; nor were meta-analyses included. We present a systematic review of studies from North America and Europe, since data are lacking from other continents. Risk is also difficult to quantify elsewhere due to the various products, compositions and usage practices involved.MethodsEpidemiological studies were identified that related pancreatic cancer to use of snuff, chewing tobacco or unspecified smokeless tobacco. Study details and effect estimates (relative risks or odds ratios) were extracted, and combined by meta-analyses.ResultsNine North American and two Scandinavian studies were identified. Reporting was limited in four studies, so only seven were included in meta-analyses, some providing results for never smokers, some for the overall population of smokers and non-smokers, and some for both.Giving preference to study-specific estimates for the overall population, if available, and for never smokers otherwise, the random-effects estimate for ever smokeless tobacco use was 1.03 (95% confidence interval 0.71–1.49) based on heterogeneous estimates from seven studies. The estimate varied little by continent, study type, or type of smokeless tobacco.Giving preference to estimates for never smokers, if available, and overall population estimates otherwise, the estimate was 1.14 (0.67–1.93), again based on heterogeneous estimates. Estimates varied (p = 0.014) between cohort studies (1.75, 1.20–2.54) and case-control studies (0.84, 0.36–1.97). The value for cohort studies derived mainly from one study, which reported an increase for never smokers (2.0, 1.2–3.3), but not overall (0.9, 0.7–1.2). This study also contributed to increases seen for snuff use and for European studies, significant only in fixed-effect analyses.The studies have various weaknesses, including few exposed cases, reliance in cohort studies on exposure recorded at baseline, poor control groups in some case-control studies, and lack of a dose-response. Publication bias, with some negative studies not being presented, is also possible.ConclusionAt most, the data suggest a possible effect of smokeless tobacco on pancreatic cancer risk. More evidence is needed. If any risk exists, it is highly likely to be less than that from smoking.

Cigarette smoking, environmental tobacco smoke exposure and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition

“…However, it has been found to be more carcinogenic than blond tobacco, 29 which would be in contrast with our results. Further, smokeless tobacco use may also affect pancreatic cancer risk and is most common in Scandinavian countries, 30 where it may have an additional effect on pancreatic cancer risk. Since heterogeneity by European region was not statistically significant and the number of pancreatic cases in Southern European countries was relatively small, our findings need to be confirmed in future cohort studies including a larger number of cases.…”

Perceptions of relative risk of disease and addiction from cigarettes and snus.

“…No association for oral cancer was also the conclusion in a study by Rosenquist (2005) and in a review article by Rodu and Jansson (2004). Sponsiello-Wang, Weitkunat and Lee (2008) looked specifically at the association between ST and pancreatic cancer, as earlier studies had identified this as a particular health hazard for snus users (Boffetta et al, 2008).…”

Smoking Is Related to Pancreatic Fibrosis in Humans

“…To date, no statistical relationship between passive smoking and the development of PC has been reported in the literature ( 4,10 ). Additionally, no relationship between smokeless tobacco and PC was observed in a recent meta-analysis (relative risk 1.03, 95 % confi dence interval 0.71 -1.49) ( 11 ).…”