Downregulation of MicroRNA-330 Correlates with the Radiation Sensitivity and Prognosis of Patients with Brain Metastasis from Lung Cancer

Background: The present study sought to explore the role of microRNA-330 (miR-330) in predicting the radiation response and prognosis of patients with brain metastasis (BM) from lung cancer (LC). Methods: Patients with BM from LC were identified and classified into radiation-sensitive and radiation-resistant groups according to the overall survival rate, local and distant recurrence rate after conventional whole-brain radiation therapy. Quantitative realtime polymerase chain reaction (qRT-PCR) was used to detect miR-330 expression in serum. Receiver operating characteristic (ROC) curves were used to evaluate the prognostic value of miR-330 for the radiation sensitivity of brain metastasis from LC. Related clinical factors for radiation sensitivity were assessed by logistic regression analysis, and a survival analysis was conducted using COX regression and the Kaplan-Meier method. Results: MiR-330 exhibited lower expression in the radiation-sensitive group than in the radiation-resistant group. The area under the ROC curve of miR-330 for predicting radiation sensitivity was 0.898 (optimal cut-off value, 0.815), with a sensitivity of 71.7% and a specificity of 90.1%. After radiation therapy, patients with low miR-330 expression, compared to patients with high miR-330 expression, displayed a lower survival rate and a median survival time. MiR-330 expression was correlated with extracranial metastasis, maximum BM diameter, tumor-node-metastasis (TNM) stage and node (N) stage. Logistic regression and COX regression analyses revealed that extracranial metastasis, TNM stage, N stage and miR-330 expression were factors that influenced both radiation sensitivity and individual prognostic factors in patients with BM from LC. Conclusions: These findings indicate that the downregulation of miR-330 correlates with radiation sensitivity and poor prognosis in patients with BM from LC.