Effect of Whole-Brain and Intensity-Modulated Radiotherapy on Serum Levels of miR-21 and Prognosis for Lung Cancer Metastatic to the Brain

BACKGROUND: The goal of the present study was to explore the influence of whole-brain radiotherapy (WBRT) and intensity-modulated radiotherapy (IMRT) on serum levels of miR-21 and prognosis for lung cancer that has metastasized to the brain. MATERIAL/METHODS: Two hundred patients with lung cancer metastatic to the brain were randomized, half to the control group and half to the observation group. The observation group received WBRT and reduced-field IMRT (WBRT+RF-IMRT) and the control group received conventional-field IMRT (CF-IMRT). The total effective rate after treatment was determined. Serum levels of miR-21 were measured before and after radiotherapy with reverse transcriptase-polymerase chain reaction. In addition, tumor marker levels were measured with enzyme-linked immunosorbent assay. The relationship between miR-21 levels and tumor marker levels was assessed with a Pearson correlation coefficient test. Five-year survival was estimated with Kaplan-Meier curves. RESULTS: The total effective rate was higher in the observation group (86%) than in the control group (69%). Lower levels of miR-21 and tumor markers were seen in the observation group. Moreover, miR-21 levels were positively correlated with levels of tumor necrosis factor-α, neuron-specific enolase, SCC-Ag, and carcinoembryonic antigen. Low levels of miR-21 were associated with longer overall survival in patients with lung cancer metastatic to the brain. CONCLUSIONS: WBRT+RF-IMRT is superior to CF-IMRT for lung cancer metastatic to the brain. MiR-21 may be a marker for prediction of the efficacy of radiotherapy in this disease setting.