Exposure to a Tobacco-Specific Carcinogen Among Adolescent Smokeless Tobacco Users in Rural California, United States

From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications

Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.

Salivary Markers in Relation to Oral Squamous Cell Carcinoma in Smokeless Tobacco Users: A Literature Review

Context: Nicotine and carcinogens are present in smokeless tobacco products. Oral, esophageal, and pancreatic cancers have been seen in Smokeless tobacco users. This article aims at reviewing the available literature and summarizing the application of salivary markers in smokeless tobacco users and their association with oral squamous cell carcinoma. Evidence Acquisition: The terms “saliva or salivary”, “markers or biomarkers”, “smokeless tobacco or Chewing tobacco or snuff”, and “oral cancer or oral carcinoma or oral squamous cell carcinoma” were searched in PubMed, MEDLINE, Google Scholar, and Google databases. Original and review English-written articles published over the past 20 years were reviewed, and the appropriate papers were chosen and intently studied. A data form designed by the author was used to write the proper results. Results: Our initial search identified 135 articles, 35 of which met the criteria for entering the final study and were contained for review. In summary, these studies described 20 markers found in the saliva of smokeless tobacco users linked to oral cancer. Conclusions: In this review study, some salivary markers such as cytokines, immunoglobulins, antioxidants, etc. were reviewed. In this review, it was shown that similar changes in these markers occur in patients with cancer and smokeless tobacco users. With the development of these diagnostic markers, these may be used as a screening tool for the early detection of cancer in smokeless tobacco users.