Multidrug resistance protein and topoisomerase 2 alpha expression in non-small cell lung cancer are related with brain metastasis postoperatively

The aim of this study was to investigate association between expressions of multidrug resistance protein (MRP) and topoisomerase 2 alpha expression in non-small cell lung cancer (TOP2A) and brain metastasis operatively. The expression of MRP and TOP2A were performed using immunohistochemistry (IHC) staining, and the results were analyzed in correlation with clinicopathological data. A total of 286 NSCLC patients who underwent curative surgery between 2007 and 2013 were enrolled in this study. Positive expression of MRP and TOP2A were 62.2% and 37.8%. MRP positive expression in NSCLC was significantly correlated with tumor cell differentiation (P=0.028). TOP2A expression was significantly associated with patients’ smoking status, tumor histological type (P<0.05). The positive MRP group had significantly inferior survival rates for 2-year BMFS than did the negative MRP group (79.0% vs. 93.4%, P=0.003) by the Kaplan-Meier method and a log-rank test. Similarly, the positive TOP2A expression was inversely correlated with 2-year BMFS (84.2% vs. 93.4%, P=0.030). Multivariate analysis showed that gender, MRP expression and TOP2A expression were independent prognostic factors for BMFS (P<0.05). Positive expressions of MRP and TOP2A in the tumor tissue are associated with increased risk of developing brain metastases in NSCLC.