Exploring the Link between BMI and Aggressive Histopathological Subtypes in Differentiated Thyroid Carcinoma—Insights from a Multicentre Retrospective Study.

Simple Summary: Our study aimed to investigate the suggested association between body mass index and aggressive histopathological subtypes of thyroid cancer. Thus, we studied 3868 patients who underwent thyroidectomy from 2020 to 2022 at four European centres. We found that overweight and obese patients with papillary thyroid carcinoma had higher rates of aggressive histopathological subtypes, bilateral, multifocal tumours, and larger nodal metastases. These findings suggest that people with higher body mass index may be at an increased risk of developing more aggressive features of thyroid cancer. Obesity's role in thyroid cancer development is still debated, as well as its association with aggressive histopathological subtypes (AHSs). To clarify the link between Body Mass Index (BMI) and AHS of differentiated thyroid carcinoma (DTC), we evaluated patients who underwent thyroidectomy for DTC from 2020 to 2022 at four European referral centres for endocrine surgery. Based on BMI, patients were classified as normal-underweight, overweight, or obese. AHSs were defined according to 2022 WHO guidelines. Among 3868 patients included, 34.5% were overweight and 19.6% obese. Histological diagnoses were: 93.6% papillary (PTC), 4.8% follicular (FTC), and 1.6% Hürthle cell (HCC) thyroid carcinoma. Obese and overweight patients with PTC had a higher rate of AHSs (p = 0.03), bilateral, multifocal tumours (p = 0.014, 0.049), and larger nodal metastases (p = 0.017). In a multivariate analysis, BMI was an independent predictor of AHS of PTC, irrespective of gender (p = 0.028). In younger patients (<55 years old) with PTC > 1 cm, BMI predicted a higher ATA risk class (p = 0.036). Overweight and obese patients with FTC had larger tumours (p = 0.036). No difference was found in terms of AHS of FTC and HCC based on BMI category. Overweight and obese patients with PTC appear to be at an increased risk for AHS and aggressive clinico-pathological characteristics. [ABSTRACT FROM AUTHOR]