Influence of Body Mass Index on the Clinicopathologic Features of Papillary Thyroid Carcinoma

Background: Epidemiologic studies have demonstrated an increased risk for papillary thyroid carcinoma (PTC) with increasing body mass index (BMI). However, the relationships between excess weight and the behavior of PTC are inconsistent. The aim of this study was to evaluate the impact of excess weight on clinicopathologic features of PTC and on patient outcomes. Methods: Data from 417 patients with PTC who underwent total thyroidectomy with cervical lymph node dissection were retrospectively analyzed. On the basis of World Health Organization standardized categories of BMI, patients were divided into 4 groups: underweight, normal weight, overweight, and obese. Histopathologic tumor features, stage at diagnosis, and disease status were determined by chart review. Logistic regression models were used to define associations between BMI and clinicopathologic features of PTC. Cox proportional-hazards models were used to assess associations between BMI and locoregional recurrence. Results: Overweight (odds ratio [OR], 3.90; P = .040) and obesity (OR, 9.19; P = .012) were independent predictors of vascular invasion. Furthermore, obesity (OR, 6.14; P = .004) was an independent predictor of extrathyroidal invasion. During follow-up (median, 29 months; range, 5-87 months), 48 patients (11.5%) experienced locoregional recurrence. There were no significant differences in locoregional recurrence of PTC among BMI groups. When adjusted for other confounding factors, extrathyroidal invasion (OR, 8.35; P < .001), vascular invasion (OR, 3.57; P < .001), cervical lymph node metastasis (OR, 3.71; P = .009), and advanced tumor-node-metastasis stage (OR, 3.81; P < .001) were identified as independent factors for locoregional recurrence. Conclusions: Higher BMI was associated with extrathyroidal invasion and vascular invasion in patients with PTC, which suggests that excess weight is associated with aggressive clinicopathologic features of PTC. But patients with higher BMI did not have an increased risk for developing postoperative complications and locoregional recurrence.