Should doctors advocate snus and other nicotine replacements? No

Abstract

Health hazards Epidemiological studies of the effects of snus are often undermined because it is commonly used along with smoked tobacco and alcohol.7 Different lifestyle factors and patterns of use in different countries preclude any Cochrane-style meta-analysis, but the two recent reports summarise the current state of knowledge.4 5The expert group of the International Agency for Research on Cancer has concluded that smokeless tobacco is carcinogenic to humans,8 and the European Commission report cites studies by the Swedish Institute of Public Health and the Karolinska Institute as evidence that snus is carcinogenic.9The obvious entry point to research on snus is the oral cavity. Mucosal changes, known as snus induced lesions or leucoplakia, are inevitable and potentially precancerous with a gradient in severity suggesting a dose response.10 Lesions in the local epithelium are reversible on quitting but gingival retractions are not.In India, a 10 year follow-up study has shown that oral cancers invariably arise from pre-existing leucoplakia.11 In the US, oral cavity cancer was found in patients who were exclusive users of smokeless tobacco and who had no exposure to alcohol.12 Studies in India, Pakistan, and the Sudan reported large increases in the risk for oral cancers related to the use of various smokeless tobacco products,4 and the International Agency for Research on Cancer has stated, “There is sufficient evidence that smokeless tobacco causes oral cancer.”8There is particularly strong evidence of a causal relation between smokeless tobacco and pancreatic cancer, notably from the Swedish construction workers cohort13 and the Lutheran brotherhood cohort in the US.14The INTERHEART study covering 52 countries showed an increased risk of cardiovascular disease in all forms of tobacco combined.15 A recent follow-up of a large US cohort showed that compared with men who had never used any tobacco product, men who quit tobacco use entirely or switched to smokeless products had significantly higher relative risks of cardiovascular disease, particularly the switchers.16 The EC report concluded that smokeless tobacco has a significant effect on myocardial infarction.4A cohort study based on the Swedish Birth Registry showed an increased risk of premature birth and pre-eclampsia among snus users compared with non-users of any tobacco.17