Infrequent tooth brushing and teeth lost may increase the risk of oral and pharyngeal cancers: A nationwide population-based cohort study in Korea.

Abstract

Background: Oral and pharyngeal cancers are emerging and troublesome diseases worldwide. Although poor oral hygiene behaviors and parameters affecting oral health have been considered as potential risk factors of oral and pharyngeal cancers including smoking and alcohol consumption for decades, study results have been inconsistent. Longitudinal studies regarding the association between poor oral hygiene behaviors and parameters of oral health and the occurrence of oral and pharyngeal cancers have been lacking. We aimed to investigate this relationship in a nationwide general population-based cohort.Methods: We included data on demographics, past history, and laboratory findings for 150,774 subjects without teeth lost from the Korean National Health Insurance System-Health Screening Cohort. The presence of periodontal disease and parameters of oral health, including frequency of tooth brushings, dental visits for any reason, professional teeth scaling, and number of teeth lost, were investigated. Oral and pharyngeal cancers were defined by the International Statistical Classification of Diseases, 10th Revision, codes of C00-C14.Results: During a median 11.1 years of follow-up, 1,155 (0.77%) oral and pharyngeal cancers occurred. Based on multivariable analysis, after adjusting for demographics, alcohol consumption, smoking status, regular exercise, body mass index, systolic blood pressure, blood and urinary laboratory findings, and parameters of oral health including frequent tooth brushing (three or more times per day) were related to a lower risk of oral and pharyngeal cancers (hazard ratio [HR]: 0.78, 95% confidence interval [CI]: 0.66–0.93, p=0.005). An increased number of teeth lost (≥15) was positively associated with occurrence of oral and pharyngeal cancers (HR: 1.71, 95% CI: 1.26–2.31, p=0.001 in model 1; HR: 1.68, 95% CI: 1.24–2.28, p<0.001 in model 2; HR: 1.66, 95% CI: 1.22–2.25, p=0.001 in model 3; p-value for trend test for HR <0.001).Conclusions: The occurrence of oral and pharyngeal cancers decreased with more frequent tooth brushing (three or more times per day) and increased with the number of teeth lost. With regards to the prevention of oral and pharyngeal cancers, improving oral hygiene may have a significant contribution.