High-level CXCR4 expression correlates with brain-specific metastasis of non-small cell lung cancer.

Background: Brain-specific metastasis occurs frequently in lung cancer, and the mechanism is still unclear. The present study was designed to investigate the correlation between CXCR4 expression and brain-specific metastasis of non-small cell lung cancer.

Methods: The brain metastatic tumors and lung cancer tissues from 32 patients with solitary brain metastasis of non-small cell lung cancer (M1 group), who underwent combined surgical treatment from January 1998 to June 2008, and 32 paired patients without distant metastasis (M0 group) and 30 patients with primary brain tumor, were examined by immunohistochemistry to detect the expression of CXCR4 protein. The difference of CXCR4 expression was compared by the McNemar χ(2) test or Fisher's exact test. Estimation of survival was calculated with the Kaplan-Meier method, and the statistical differences were analyzed with the log-rank test.

Results: Overexpression of CXCR4 protein was observed in 29 (90.6%) M1 non-small cell lung cancers and in all (100%) brain metastatic tumors, which was significantly higher than that in the paired M0 non-small cell lung cancer and the primary brain tumors, respectively (p = 0.000). The 3- and 5-year cumulative survival rates of patients with solitary brain metastasis of lung cancer were 21.9 and 12.5%, significantly lower than the corresponding survival rates of M0 group patients (p = 0.005).

Conclusions: CXCR4 protein was highly overexpressed in M1 non-small cell lung cancer and brain metastatic tumors, which indicated that high-level CXCR4 expression correlates with brain-specific metastasis of non-small cell lung cancer.