Diabetes Mellitus And Head And Neck Cancer

Rejane FIGUEIREDO, Faculty of Public Health at University of Sao Paulo, Department of Epidemiology, Sao Paulo, Brazil, Brazil

1 Department of Epidemiology, Faculty of Public Health at University of Sao Paulo, Sao Paulo, Brazil
2 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet
3 Department of Community Medicine, Faculty of Health Sciences, University of Tromsø, The Arctic University of Norway, Tromsø, Norway
4 Department of Research, Cancer Registry of Norway, Oslo, Norway
5 Genetic Epidemiology Group, Folkhälsan Research Center, University of Helsinki, Helsinki, Finland

Purpose: Diabetes mellitus (DM) is directly associated with some cancers. However, studies on the association between DM and head and neck cancer (HNC) have rendered controversial results. Assessing DM and cancer, emphasis should be given to metformin, a medication used for DM type 2, which is shown to be inversely associated with some cancers. The objective of this study was to evaluate the association between DM and HNC, as well as the impact of metformin use on the risk of HNC.
Methods: This case-control study included 1021 HNC cases with squamous cell carcinoma, histologically confirmed, admitted in five large hospitals in the state of São Paulo, from 2011 to 2014. A total of 1063 controls were selected in the same hospitals and were frequency-matched to cases by sex and age (in 5-year groups). In order to assess the risk of CCP associated with DM, odds ratios (OR) and 95% confidence intervals (CI 95%) were estimated using unconditional logistic regression.
Results: Diabetic participants had an inverse risk of HNC (OR=0.68; 95% CI: 0.49-0.95), and this inverse association was more intense among diabetic metformin users (OR=0.54; 95% CI: 0.29-0.99). Diabetic metformin users that were current smokers (OR=0.13; 95% CI: 0.04-0.44) or had an alcohol consumption of >40 g/day (OR=0.31; 95% CI: 0.11-0.88) had lower risk of HNC than non-diabetic participants.
Conclusion: DM patients have um inverse risk of HNC and the use of metformin may at least partially explain this association.
Funding source: This work was supported by the São Paulo Research Foundation (FAPESP, grant  2010/51168-0, 2013/20548-0,  2013/21702-3, 2014/18893-4).