Higher microRNA-221 and lower microRNA-451 expression are associated with poor prognosis in patients with thyroid papillary carcinoma

BACKGROUND: To analyze the relationship between serum microRNA-221 and microRNA-451 expression and the pathological features and prognosis of patients with thyroid papillary carcinoma. METHODS: Cross-sectional study that included 120 patients with papillary thyroid cancer treated at the hospital and 120 healthy volunteers selected as the control group who underwent physical examination. The relative expression levels of microRNA-221 and microRNA-451 were compared between the thyroid papillary carcinoma group (prior to treatment) and the control group. Additionally, microRNA-221 and microRNA-451 expression levels were analyzed in patients with papillary thyroid carcinoma across different pathological characteristics. RESULTS: Serum microRNA-221 relative levels were significantly higher (p<0.001) in the papillary carcinoma group compared to the control group, while microRNA-451 levels were higher in the control group (p<0.001). In the papillary carcinoma group, microRNA-221 expression was significantly higher in patients with extracapsular invasion (p<0.001), lymphatic metastasis (p=0.003), and poor prognosis (p<0.001). Conversely, microRNA-451 expression was significantly lower (p<0.001) in patients with extracapsular invasion, lymphatic metastasis and poor prognosis. In the multivariate logistic regression analysis, morphological features suggestive of an aggressive clinical behavior (extracapsular invasion and lymphatic metastasis) were related to high expression of microRNA-221 and low expression of microRNA-451 in patients with thyroid papillary carcinoma (p<0.001). CONCLUSIONS: Serum microRNA-221 and microRNA-451 expression levels are significantly higher and lower, respectively, in patients with papillary thyroid carcinoma, particularly in patients with morphological features suggestive of an aggressive clinical behavior (extracapsular invasion and lymphatic metastasis) and, therefore, of a poor prognosis.