JMIR Publications

ABSTRACT

Background:

Tobacco use has been identified as a risk factor for oral cancer worldwide. However, relative oral cancer incidence among people who smoke cigarettes, use smokeless tobacco products (ST), have transitioned from cigarettes to ST (“switchers”), quit both cigarettes and/or ST (“quitters”), or never used tobacco has not been well studied.

Objective:

We aim to present population-based oral cancer incidence rates for people who smoke cigarettes, use ST, and switched from cigarette to ST use to test the principle of tobacco harm reduction.

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 using combined data from 2014-2017. 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 incidence 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.