It has been recently revealed that type 2 diabetes is a risk factor for tumorous proliferation at different sites (1). Breast and colon cancers were the first tumors for which an epidemiological correlation was demonstrated between this glucose metabolism disorder and tumor incidence (2). The “western lifestyle,” first of all obesity, increases the risk of not only type 2 diabetes but also of overall cancer promotion (3).
Swelling of the parotids and a decreased salivary flow rate caused by degenerative alterations in the acinar cells are common concomitants of diabetes and dyslipidemias (4,5). However, no data are available concerning the epidemiological correlation between metabolic disorders and salivary gland tumors.
In the present work, a retrospective controlled study was performed to clarify the possibility of an association between type 2 diabetes, obesity, and salivary gland tumors. Clinical data on 438 inpatients were analyzed on the basis of their case histories. In 224 patients, salivary gland tumors had been surgically removed and histologically diagnosed (SGT group). The mean age of these patients was 51.2 years (range 23–87). A total of 118 were men and 106 were women. Their tumors were predominantly benign (166 cases, 74.2%), and a majority of them were located in the parotid. The rate of malignancies was 25.8% (58 cases), and the most frequent locations were the accessory glands of the palate. Two hundred and fourteen randomly selected patients undergoing dental surgery served as the control group. They had no tumorous lesions in the oral or maxillofacial region. Their mean age was 50.8 years (range 24–80). A total of 104 were men and 110 were women. Fasting blood glucose levels were routinely measured repeatedly within 4 days before the surgical intervention. The level was regarded as pathological only if it was repeatedly higher than normal (>6.9 mmol/l). Patients with known and treated disease or with a newly diagnosed high fasting glucose levels were included in the type 2 diabetic group. BMI was also registered in the case histories. Patients with BMI >30 kg/m2 were regarded as obese. The χ2 test was used for the statistical analysis. A probability level of 5% was taken as a limit of statistical significance.
Type 2 diabetes was established in 51 patients (22.8%) of the SGT group and in 14 subjects (6.5%) in the tumor-free control group (P < 0.001). Among the diabetic and nondiabetic patients of the SGT group, the rates of histologically malignant tumors were 26.6 and 23.5%, respectively (P > 0.05). Obesity was registered in 102 patients (45.5%) in the SGT group and in 38 subjects (17.7%) in the control group (P < 0.001). The rates of malignant tumors among the obese and nonobese SGT patients were 27.8 and 23.5%, respectively (P > 0.05).
These findings permit a novel hypothesis concerning the epidemiological association between type 2 diabetes, obesity, and salivary gland tumors. However, there were no close correlations between these metabolic disorders and the malignancy rate of the tumors.
