Risk Factors for Malignancy of Thyroid Nodules in Patients Undergoing Thyroid Resection

Background: An accurate diagnosis of thyroid nodules is crucial for avoiding unnecessary surgical procedures and making timely treatment possible. The objective of the present study was to evaluate the diagnostic accuracy of fine-needle aspiration biopsy (FNAB) using histopathological findings as the reference standard. Patients with the diagnostic categories (DCs) III, IV, and V were subjected to special analysis. In addition, the authors assessed whether other factors, including age, gender, body mass index (BMI), obesity, and histopathologically confirmed lymphocytic thyroiditis, had an impact on the occurrence of malignant tumors. Methods: We performed a retrospective analysis of 535 patients (with a mean age of 52.3) who underwent thyroid surgery between October 2022 and September 2023 at the Department of Endocrine Surgery at the University Hospital in Krakow. To assess the reliability of FNAB, the results obtained using the Bethesda classification were compared with the histopathological results. Results: The risk of malignancy (ROM) values for DCs I-VI were 38.1%, 15.6%, 29.8%, 18.6%, 91.0%, and 93.2%, respectively. DC V (OR 62.34, p < 0.0001) and an age ≤ 50 (OR = 2.31, p < 0.006) had statistically significant effects on the risk of thyroid cancer. DCs III and IV were not statistically significantly associated with the risk of malignancy (OR = 1.68, p = 0.16; OR = 1.51, p = 0.3, respectively). There were no statistically significant differences in sex, BMI, or obesity between the patients with benign and malignant lesions. Conclusions: DC V is associated with a high likelihood of malignancy, especially in patients under 50 years of age, and, therefore, surgery is indicated in this category of subjects. In DCs III and IV, the risk of malignancy is lower, and conservative management with active clinical and ultrasound surveillance can be considered. In patients < 50 years of age, with Bethesda categories III and IV, surgical treatment should be considered.