SAT-344 The Effect of Preexisting Diabetes on the Risk and Features of Thyroid Cancer in Patients Undergoing Thyroidectomy: An International Multicentric Study

Abstract Disclosure: R.D. Paparodis: None. E. Karvounis: None. G. Simeakis: None. I. Androulakis: None. D.P. Askitis: None. S. Livadas: None. A. Rizoulis: None. V. Papanikos: None. N. Mastronikolis: None. D. Zianni: None. C. Massouras: None. I. Perogamvros: None. A. Boniakos: None. N.G. Angelopoulos: None. D. Bantouna: None. A. Kapezanou: None. O. Aporelli: None. S. Imam: None. J.C. Jaume: None. Introduction: Thyroid cancer has been associated with all forms of diabetes in some studies, but others contradicted these findings. Given that the metabolic perturbations that lead to type 2 diabetes (DM2) and the autoimmunity-mediated inflammation present in type 1 diabetes and LADA (DM1) both seem to affect the risk for cancers in several other organs, we designed the present study to assess their effects on thyroid cancer development and aggressiveness. Methods: We performed a retrospective data analysis of patients undergoing thyroidectomy over 10 years in 2 centers in the US and 13 in Greece. We collected data on gender, pre-existing DM, TSH, and surgical pathology. Patients were split in those with DM2, autoimmune diabetes (type 1 + LADA = DM1) and unaffected individuals (controls=CON). Results: We reviewed n=9461 consecutive thyroidectomy cases and enrolled n= 3459 patients; n=980 males (28.3%). These included DM2 n=361, DM1 n=11 and CON n=3087, all with similar preoperative serum TSH (p>0.05). There were more males in the DM subgroups compared to CON. Overall, n=1766 thyroid cancers were identified: Papillary n=1667, Follicular n=23, Hürthle cell n=28, Medullary n=38, Poorly differentiated n=6, Anaplastic n=1, Lymphoma n=1, Other n=2. The incidence of thyroid cancer by surgical pathology was not different between DM and non-DM patients, and the same holds true for the different histological subtypes’ ratios. Microscopic extrathyroidal extension (ETE) and capsular invasion was less common in DM1 and DM2, but gross ETE was more common in DM2 compared to CON (p<0.05). Tumor recurrence was more common in CON compared to DM patients (p<0.05). Lymph node involvement, distant metastasis and the number of I-131 treatments required, were equally distributed among all groups (p>0.05). Background lymphocytic thyroiditis was more common in DM1, and significantly less common in DM2 patients compared to controls (p<0.001). Conclusions: Diabetes does not seem to increase the risk for thyroid cancer in our international, multicenter cohort. Patients with diabetes tend to have lower risk of thyroid cancer extension beyond the gland’s capsule, though DM2 patients develop more aggressive extensions when these are present. Tumor aggressiveness with regard to lymph node or distant metastasis does not appear to be affected by the presence of diabetes. Presentation: Saturday, July 12, 2025