Environmental and lifestyle factors and risk of thyroid carcinoma: a cross-sectional study.

PURPOSE: The incidence of differentiated thyroid carcinoma (DTC) is increasing, and environmental factors, including lifestyle and endocrine-disrupting chemicals (EDCs) exposure, have been advocated as having an etiologic role. To investigate the relationship between DTC, EDCs exposure, and lifestyle in a population from two Italian regions. METHODS: A cross-sectional study evaluating chemical exposure, lifestyle, and DTC diagnosis in subjects with thyroid nodules, undergoing Fine Needle Aspiration Cytology from May 2019 to February 2021. 193 patients were split into groups based on cytological diagnosis: group A, benign or low-risk (TIR2-TIR3A); group B, high-risk (TIR3B-TIR4-TIR5). Age, sex, weight, height, body mass index (BMI), waist circumference (WC), thyroid hormone profile, lifestyle variables, and serum EDCs levels were compared. RESULTS: The percentage of male patients was significantly higher in group B (p = 0.033), as well as the prevalence of obesity (p = 0.001) and BMI (p = 0.013). Visceral obesity was higher in group B, without reaching statistical significance (70.4% vs. 58.7%, p = 0.252), while WC was significantly higher in group B (p = 0.008). EDCs serum levels were not significantly higher in group B. A multivariable analysis found a significant association between high-risk cytology and WC (OR 1.04, 95% CI 1.01–1.08, p = 0.027). Considering patients with obesity, a linear correlation was observed between WC and bis(2-ethylhexyl) phthalate (DEHP) levels (r:0.40; p = 0.034). CONCLUSION: Obesity could have a role in DTC development. Furthermore, the WC and DEHP levels correlation in patients with obesity supports the hypothesis of an interaction between EDCs exposure and adipose tissue excess in increasing DTC risk.