Type 2 diabetes, obesity and their relation to the risks of thyroid cancer

Abstract

Abstract Purpose Patients with type 2 diabetes (T2DM) and obesity are generally known to have increased risk of various types of cancer, though studies addressing associations between T2DM/obesity and thyroid cancer are inconclusive. The aim of our study was to evaluate patients in a euthyroid status with histological results. Methods A retrospective study in 184 patients was performed. Three cohorts were established according to tumour histology; malignant (M), benign (B) and low-risk carcinoma (MB). Patient histories were taken, and biochemical testing and fine needle biopsy with molecular testing were performed. Fisher’s exact test and Kruskal-Wallis one-way ANOVA of ranks were used for statistical analysis. Results The M (39.1%), B (57.6%) and MB (3.3%) cohorts had comparable age (p = 0.4), BMI (p = 0.452), glycaemia (p = 0.834), Hb1AC (p = 0.157) and HOMA-IR (p = 0.235). T2DM patients had larger thyroid gland volumes (28.8 vs 17.6 mL; p = 0.001) compared to the cohort with normal glucose tolerance. Compared to women, men had more frequently present distal metastases (p = 0.017), minimally invasive disease (p = 0.027), more advanced staging (p = 0.01) and positive pathogenic mutations in the TERT gene (p = 0.009); these results were also significant for the diabetic male cohort (p = 0.026). Conclusion Type 2 diabetes and obesity are not risk factors for thyroid cancer, but a subgroup of males seem to have thyroid cancers of poorer prognosis. In general, diabetic patients with insulin resistance and hyperinsulinemia are also prone to have a goitre.