Relationship between obesity, diabetes and the risk of thyroid cancer

Purpose: Analyze the relationship between obesity and type-2 diabetes mellitus (DM) and the development of differentiated thyroid cancer (DTC). Materials and methods: A randomized case-controlled retrospective chart review of outpatient clinic patients at an academic medical center between January 2005 and December 2012. DTC patients were compared to two control groups: primary hyperparathyroidism (PHPTH) patients with euthyroid state and Internal Medicine (IM) patients. Exposure variables included historical body-mass-index (BMI), most recent BMI within 6 months and DM. Multivariate logistic regressions adjusting for gender, age, and year of BMI assessed the adjusted Odds Ratio (OR) of DTC with both BMI and DM. Results: Comparison of means showed a statistically significant higher BMI in DTC (BMI = 37.83) than PHPTH, IM, and pooled controls, BMI = 30.36 p = <0.0001, BMI = 28.96 p = <0.0001, BMI = 29.53 p = <0.0001, respectively. When compared to PHPTH, DM was more frequent in DTC (29% vs. 16%) and prevalence trended towards significance (p = 0.0829,95% CI = 0.902-5.407). BMI adjusted OR was significant when compared to PHPTH, IM and pooled controls: 1.125 (p = 0.0001), 1.154 (p = <0.0001), and 1.113 (p = <0.0001), respectively. DM adjusted OR was significant when compared to PHPTH and pooled controls at 3.178 (95% 1.202,8.404, p = 0.0198) and 2.237 (95% 1.033,4.844, p = 0.0410), respectively. Conclusion: Our results show that obesity and, to a lesser degree, DM are significantly associated with DTC. BMI in particular was a strong predictive variable for DTC (C = 0.82 bivariate, C = 0.84 multivariate). (C) 2015 Elsevier Inc. All rights reserved.