Association between tooth loss and orodigestive cancer mortality in an 80-year-old community-dwelling Japanese population: a 12-year prospective study

Background: A growing body of evidence has indicated a possible association between oral and gastrointestinal (orodigestive) cancers and periodontal disease or tooth loss. However, the evidence remains contradictory. This study investigated whether tooth loss, which is indicative of poor oral health and a potential source of oral infections, is associated with death from orodigestive cancer. Methods: The study included 656 subjects in Fukuoka prefecture, Japan, who were 80 years old at baseline in 1998. All subjects underwent oral clinical examination and answered a questionnaire to determine their background characteristics. Cause of death over the 12-year follow-up was recorded from the registers at the Public Health Centers and classified according to the WHO International Classification of Diseases. Statistical analysis of associations was performed using Kaplan-Meier and Cox multivariate regression analyses. Results: A significant association was observed between tooth loss (continuous variable) and cancer death (hazard ratio (HR): 1.03, 95% confidence interval (CI): 1.00-1.07), after adjustment for potential confounders, including sex and smoking status. However, that association became insignificant in the fully adjusted model. On the other hand, tooth loss was significantly associated with orodigestive cancer (HR: 1.06, 95% CI: 1.01-1.13), even in the fully adjusted model including place of residence as a part of socioeconomic status. Conclusions: This study provides the first evidence in a prospective study in a Japanese population that tooth loss is associated with increased orodigestive cancer mortality, although the causality remains unclear.