Tooth loss and risk of colorectal cancer: a dose–response meta-analysis of prospective cohort studies

Background Previous studies have indicated that tooth loss is associated with colorectal cancer risk but have presented controversial results. Methods We conducted a dose-response meta-analysis in order to investigate the correlation between tooth loss and colorectal cancer risk. Up to August 2017, six eligible studies were included in this meta-analysis. Results Our results showed statistically significant association between tooth loss and colorectal cancer (OR =1.08, 95% CI: 1.03-1.15, P<0.001). In addition, we obtained the best fit at an inflection point of every two tooth loss in piecewise regression analysis, and the summary relative risk (RR) of colorectal cancer for an increase of every two tooth loss was 1.06 (95% CI: 1.02-1.11, P<0.001). Furthermore, tooth loss was significantly associated with colorectal cancer risk in Caucasia (RR: 1.18; 95% CI: 1.09-1.28; P<0.001) and Asia (RR: 1.06; 95% CI: 1.02-1.10; P<0.001). Moreover, tooth loss was significantly associated with a higher risk of colon cancer (RR: 1.09; 95% CI: 1.02-1.17; P<0.001) and rectal cancer (RR: 1.08; 95% CI: 1.01-1.17; P<0.001). Conclusion Subgroup meta-analyses showed consistency with the primary findings. Considering these promising results, increasing tooth loss may be harmful to our health, and maintenance of our oral health is essential.