Chemokine receptor CXCR4 overexpression predicts recurrence for hormone receptor-positive, node-negative breast cancer patients.

Background: The expected outcome for hormone receptor-positive, node-negative patients should be favorable. However, some patients do develop metastatic disease and the mechanism for this observation is poorly understood. CXCR4 is a chemokine receptor that has been implicated to play a pivotal role in breast cancer growth and metastasis. Its predictive role has not been fully evaluated. We determined to see whether CXCR4 can predict outcome in this subset of patients.

Methods: We accrued and analyzed data from 101 patients with hormone receptor-positive, node-negative breast cancers. The CXCR4 level was detected using Western blots and its level was defined as either low (<6.6-fold) or high (≥6.6-fold). Primary end points were systemic cancer recurrence and death. Statistical analysis performed included Spearman's correlation, Kaplan-Meier survival analysis, and Cox proportional hazard model.

Results: Although benign breast tissues had an undetectable level of CXCR4, all 101 cancer specimens had overexpressed CXCR4 (mean 6.4 ± 3.4-fold). There were 79 patients in the low CXCR4 group and 22 patients in the high CXCR4 group. High CXCR4 overexpression was predictive of both cancer recurrence (P = .002) and overall survival (P = .0012).

Conclusion: High CXCR4 overexpression in primary tumors was predictive of worse outcomes in hormone receptor-positive, node-negative breast cancer patients.