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

## TL;DR

This study explores how environmental and lifestyle factors, including obesity and exposure to certain chemicals, might influence the risk of thyroid cancer in a population from Italy.

## Contribution

The study identifies a potential link between obesity, waist circumference, and exposure to endocrine-disrupting chemicals in thyroid cancer risk.

## Key findings

- Patients with high-risk thyroid nodules were more likely to be male and obese with higher BMI and waist circumference.
- A significant correlation was found between waist circumference and bis(2-ethylhexyl) phthalate levels in obese patients.
- Obesity and waist circumference were associated with increased risk of high-risk thyroid cytology.

## Abstract

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.

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.

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).

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.