The Role of Body Mass Index (BMI) in Differentiated Thyroid Cancer: A Potential Prognostic Factor?

Obesity has been recognized as a potential risk factor for the carcinogenesis of differentiated thyroid cancer (DTC). The aim of this observational study was to investigate the prognostic role of BMI in influencing DTC histopathological aggressiveness and the risk of tumor relapse. We enrolled 257 patients with DTC, consecutively admitted to our Institution between January 2016 and December 2023. The following variables were collected: demographic, anthropometric and clinical parameters, risk factors for DTC, surgical and radioiodine therapy, histopathological features of DTC, and biochemical markers of disease. Tumor recurrence was assessed during short-, medium- and long-term follow-up. According to BMI tertiles (e.g; I: BMI < 23.3 kg/m²; II: 23.3 ≤ BMI < 27.1 kg/m²; III: BMI ≥ 27.1 kg/m²), the clinical and histopathological characteristics did not differ between groups. The multinomial logistic regression analysis showed that BMI was not associated with clinical and histopathological aggressiveness of DTC, independently from sex, age, and risk factors for DTC onset. Moreover, BMI did not constitute a predictor of tumor recurrence during follow-up. In conclusion, BMI does not represent a predictor of clinical and histopathological aggressiveness of DTC. Since it is not a reliable marker of adiposity, BMI cannot be considered alone in evaluating the potential association between obesity and DTC prognosis.