Oral cancer risk among people who smoke, have quit smoking, use smokeless tobacco, or former smokers that use smokeless tobacco observed from state-based cancer registries

Abstract

Abstract Background Tobacco use has been identified as a risk factor for oral cancer worldwide. However, oral cancer risk among people who smoke cigarettes, use smokeless tobacco products (ST), have transitioned from cigarettes to ST (“switchers”) or quit both cigarettes and/or ST (“quitters”) has not been well studied. This study compared oral cancer incidence between 2014–2017 relative to never tobacco use.Methods We estimated incidence rates and incidence rate ratios using data from state-wide cancer registries (i.e., Colorado, Florida, North Carolina, and Texas) and population counts derived from national surveys. A random-effect meta-analysis approach was used to summarize estimates among these groups, based on multiple imputation-based incidence rate ratio estimates, by state and age groups while considering potential heterogeneity.Results A total of 19,536 oral cancer cases were identified among adult males 35 years and older in the study geographies and period. People who currently smoked cigarettes were 2.6 (95% CI = 2.0-3.3) times as likely to be diagnosed with oral cancer compared to individuals who currently used ST. The incidence rate ratio among people who currently smoke cigarettes was 3.6 (95% CI = 3.2–4.1) relative to never users, 2.4 (95% CI = 1.8–3.1) relative to switchers and 1.4 (95% CI = 1.0-2.1) among switchers relative to quitters. The incidence rate ratio of current users of ST relative to never-users was 1.4 (95% CI = 1.1–1.9).Conclusions Findings from this population-based study with a large number of oral cancer cases support lower risk of oral cancer among users of ST compared to cigarettes. Compared to those who continue to smoke, oral cancer risks can be reduced by switching to ST products or quitting all tobacco.