Transforming Growth Factor β1 Could Influence Thyroid Nodule Elasticity and Also Improve Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma

Ultrasound elastography has been a very useful tool in predicting the risk of malignant thyroid tumor for several years. The objective of this study was to determine if there is a correlation between strain ratio (SR), collagen deposition and transforming growth factor β1 (TGF-β1) expression in different types of thyroid nodules and if TGF-β1 is related to cervical lymph node metastasis. 102 nodules from 81 patients who underwent thyroid resection surgery in our hospital were retrospectively studied. All of these patients had undergone ultrasound elastography scanning before surgery. Masson staining and immunohistochemical staining were used to evaluate the ratio of expression of collagen deposition and TGF-β1. There was a significant difference between benign and malignant thyroid nodules in SR (8.913 ± 11.021 vs. 1.732 ± 0.727, p = 0.000), collagen content (0.371 ± 0.125 vs. 0.208 ± 0.057, p = 0.000) and TGF-β1 expression (0.336 ± 0.093 vs. 0.178 ± 0.071, p = 0.000). A cutoff of 2.99 for SR measurement was selected for the highest Youden index for predicting malignant thyroid nodules, which yielded 87.88% sensitivity, 100% specificity, 100% positive predictive value, 83.72% negative predictive value and 92.15% accuracy. Expression of collagen and TGF-β1 was positively correlated with SR measurements (coefficient = 0.839 for collagen and 0.855 for TGF-β1, p = 0.000). Among 61 nodules with papillary thyroid carcinoma, the average SR for the metastasis group was higher than that for the non-metastasis group (10.955 ± 13.805 and 7.852 ± 7.931, respectively), but without statistical significance (p = 0.287). Collagen deposition was significantly higher in the metastasis group than in the non-metastasis group (0.421 ± 0.091 vs. 0.353 ± 0.118, p = 0.011). TGF-β1 expression was also significantly higher in the metastasis group than in the non-metastasis group (0.378 ± 0.0.69 vs. 0.328 ± 0.091, p = 0.016). To conclude, TGF-β1 may contribute to thyroid nodule elasticity by promoting collagen deposition. In papillary thyroid carcinoma, overexpression of TGF-β1, as well as collagen deposition, may be a risk factor for cervical lymph node metastasis.