Oral Cancer Risk Assessment for Different Types of Smokeless Tobacco Products Sold Worldwide: A Review of Reviews and Meta-analyses

Abstract

Abstract Smokeless tobacco (SLT) use is a significant cause of lip and oral cavity cancers. Globally, oral cancer prevalence is strongly linked to the types of tobacco products used, their chemical composition, and their pattern of use. Except snus, all SLT products sold in different World Health Organization regions are strongly associated with oral cancer incidence. Shammah showed the highest association OR with 95% confidence intervals (CI; OR, 38.74; 95% CI, 19.50–76.96), followed by oral snuff (OR, 11.80; 95% CI, 8.45–16.49), gutkha (OR, 8.67; 95% CI, 3.59–20.93), tobacco with betel quid (OR, 7.74; 95% CI, 5.38–11.13), toombak (OR, 4.72; 95% CI, 2.88–7.73), and unspecified chewing tobacco (OR, 4.72; 95% CI, 3.13–7.11). Most SLT products containing high levels of carcinogenic tobacco-specific nitrosamines (TSNA) exhibit a high risk of oral cancer. There is an urgent need to frame and implement international policies for oral cancer prevention through legal control of the TSNA levels in all SLT product types. Prevention Relevance: Most smokeless tobacco products sold worldwide, mainly shammah, toombak, gutkha, betel quid with tobacco, and dry snuff, are associated with a high risk of oral cancer. A high concentration of tobacco-specific nitrosamines in smokeless tobacco products is the major causative factor for oral cancer development.