[Correlation between obesity and ultrasonic malignant features of papillary thyroid carcinoma]

Objective: To explore the correlation between obesity and ultrasonic malignant features of papillary thyroid carcinoma (PTC). Methods: A retrospective analysis was conducted on 8 483 patients who underwent thyroid surgery and were postoperatively diagnosed with PTC at China-Japan Union Hospital of Jilin University between January 2008 and December 2017. The cohort included 1 580 males and 6 903 females, with the age [M(Q₁,Q₃)] of 42.0(36.0,49.0) years. Patients were divided into the non-obese group and the obese group based on whether their body mass index was≥28 kg/m². Propensity score matching (PSM) was employed to conduct 1∶1 matching for variables such as gender and history of diabetes. Core ultrasound features and thyroid imaging reporting and data system (TIRADS) scores were compared between the two groups. Subgroup analyses were performed based on gender. A multivariate logistic regression model was employed to analyze the correlation between obesity and malignant ultrasonic features of PTC. Results: After PSM, each group consisted of 1 762 patients, and there were no statistically significant differences between the two groups in terms of gender, diabetes history, family history of thyroid cancer, the maximum tumor diameter was>1 cm, multifocality, extraglandular invasion, lymph node metastasis, and Hashimoto's thyroiditis (all P>0.05). The proportion of punctate hyperechoic foci (microcalcifications) in the obese group was lower than that in the non-obese group [33.1% (584/1 762) vs 37.9% (668/1 762), P=0.009]. Subgroup analysis by gender revealed that among obese males, the proportions of markedly hypoechoic nodules [4.9% (34/692) vs 2.7% (19/694)] and coarse calcifications [25.0% (173/692) vs 19.3% (134/694)] were higher than those in the non-obese group, while the proportion of punctate hyperechoic foci was lower [35.6% (246/692) vs 42.4% (294/694)] (all P<0.05). Among females, there were no statistically significant differences in any ultrasound features between the obese and non-obese groups (all P>0.05). There was no statistically significant difference in the overall distribution of TIRADS risk categories in thyroid nodules between the obese and non-obese groups (P=0.054). The multivariate logistic regression analysis revealed that obesity was a significant factor associated with the presence of peripheral calcification or punctate hyperechoic foci in thyroid ultrasound findings (OR=0.80, 95%CI: 0.70-0.93). Conclusions: Obesity is associated with a decreased display rate of a key malignant ultrasound feature in PTC -- punctate hyperechoic foci. The incidence of this feature is lower in obese males compared to non-obese males.