A systematic review of cancer risk among users of smokeless tobacco (Swedish snus) exclusively, compared with no use of tobacco.

The main objective of this systematic review was to assess cancer risk, and mortality after cancer diagnosis, for exclusive users of Swedish snus, compared with non-users of tobacco. We followed international standards for systematic reviews and graded our confidence in the risk estimates using the GRADE approach. Our search gave 2450 articles, of which 67 were assessed in full text against our inclusion criteria. Of these, 14 cohort-studies and one case-control study were included in the review. The studies investigated risk of cancer in the oral cavity or oropharynx (3 studies), esophagus (1 study), stomach (1 study), pancreas (2 studies), colorectum (2 studies), anus (1 study) and lung (1 study), as well as malignant lymphoma (1 study), leukemia and multiple myeloma (1 study), melanoma (1 study), any cancer (1 study) and mortality after cancer diagnosis (4 studies). Cancer risk could only be evaluated in men as there was a general lack of data for women. All included studies were evaluated to have a moderate risk of bias, mostly related to validity of exposure information. An increased risk of cancer of the esophagus, pancreas, stomach and rectum as well as an association between use of snus and increased mortality after a cancer diagnosis was reported. Our confidence in the various risk estimates varied from moderate through low to very low.

Are the health risks of moist oral snuff (snus) underestimated? / Er helserisikoen ved snus undervurdert?

The use of moist oral snuff (snus) has increased significantly, particularly among young adults who have not previously smoked. Snus increases the risk of cancer, cardiovascular disease, type-2 diabetes and birth defects.

A possible role of chitin in the pathogenesis of asthma and allergy.

Chitin is the second most abundant polysaccharide in the world; it is found in insects, parasites and fungi. Chitinases break down chitin, and are a part of the defence mechanism against chitin-containing parasites in lower life forms. This review is based on the results of PubMed-searches using the search-terms: chitin, chitinase, allergy and asthma. Research in murine models has proved that chitin is a size-dependent microbial-associated molecular pattern, with the ability to induce an immunological response via pattern recognition receptors. Medium-sized chitin micro-particles (CMPs) have been shown to induce inflammation, while small-sized CMPs reduce inflammation. The amount of acidic mammalian chitinase correlates with asthma, and the enzyme has been shown to induce chemokine secretion in murine lungs. The high prevalence of asthma among people working with chitinous substances, such as crabs and fungi, supports the hypothesis that chitin might be an allergen playing a role of significance in the development of asthma. This new knowledge about chitin and chitinases, combined with the hygiene-hypothesis, may contribute to a model for the pathogenesis of allergic conditions where chitin and chitinases are potential therapeutic targets.