Predictors of Thyroid Malignancy in Graves' Disease: The Role of Body Mass Index in a Surgical Cohort.

Abstract

The incidence of thyroid carcinoma in patients with Graves' disease (GD) has increased, with reported rates ranging from 1% to 21%. While thyroid nodules are a well-established risk factor, the role of body mass index (BMI) in predicting malignancy in GD remains unclear. This study aimed to evaluate the prevalence of thyroid cancer in GD and identify independent predictors to improve preoperative risk stratification. We retrospectively analyzed 206 consecutive patients who underwent thyroidectomy for GD between 2016 and 2024. Demographic characteristics, preoperative biochemical parameters, and postoperative histopathological findings were reviewed. Patients were classified as malignant (n = 42) or benign (n = 164). All malignancies were papillary thyroid carcinoma. The mean age was 42.3 ± 13.2 years, and 74.8% were female. Age was not associated with malignancy. Female sex was more prevalent in the malignant group (88.1% vs. 71.3%; p = 0.026). Patients with malignancy had significantly higher BMI (28.1 ± 4.2 vs. 25.5 ± 4.3 kg/m²; p = 0.001) and a higher rate of thyroid nodules (66.7% vs. 31.1%; p < 0.001). Biochemical parameters were not predictive. Multivariable analysis identified female sex (OR = 2.90, p = 0.045), thyroid nodules (OR = 3.27, p = 0.002), and BMI (OR = 1.13 per kg/m², p = 0.005) as independent predictors. BMI alone showed moderate discrimination (AUC = 0.67). Higher BMI is independently associated with thyroid malignancy in GD and may serve as a clinically relevant adjunctive risk marker. When combined with thyroid nodules and sex, BMI may enhance preoperative risk stratification and support more individualized surgical decision-making in patients with GD.