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

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.