Disorders of glucose metabolism and risk of oral cancer.

Alcohol and tobacco are considered as major risk factors for oral cancer (OC). In the developed countries reduction of alcohol and tobacco consumption has achieved favorable decreasing trends in OC morbidity and mortality over the last decades. At the same time the earlier very high male-female OC ratio showed a declining tendency all over the world. This trend used to be simply interpreted by the increasing exposure to tobacco and alcohol among women. However, literary data support an enhanced prevalence of women among non-smoker non-drinker OC cases. These findings focused the attention for further underlying mechanisms in the initiation of OC, such as metabolic and hormonal disorders. Insulin resistant states (metabolic syndrome and type-2 diabetes) are sources of many human diseases. Reactive hyperinsulinemia, increased production of insulin-like growth factors, hyperglycemia and its serious consequences are all proven cancer promoters. Decreased blood perfusion of the tissues caused by diabetic macro- and microvascular lesions, extracellular matrix alterations, and defects of inflammatory and immunologic reactions in type-2 diabetes are also predictors of OC. The literary data and the authors' own results on their OC cases support the strong association of type-2 diabetes and increased cancer risk. Moreover, type-2 diabetes has a significant impact on the local invasion and metastatic progression of OC. The correlations between glucose metabolism disorders and malignancies reveal new possibilities in the prevention and treatment of OC.