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).