High Chemokine Receptor CXCR4 Level in Triple Negative Breast Cancer Specimens Predicts Poor Clinical Outcome

IntroductionBasal-like tumors or triple negative breast cancers are those that lack hormone-receptor and HER-2 expressions. They are considered to be aggressive tumors, and molecular mechanism to account for this is poorly understood. CXCR4 is a chemokine receptor that has been linked to breast cancer invasion and metastasis. We postulate that high CXCR4 overexpression level in cancer specimens predicts a poor outcome in patients with triple negative breast cancers.MethodsOne hundred fifty-one patients with triple negative breast cancers were prospectively accrued and analyzed. All had undergone standardized treatment and surveillance protocols. From each specimen, CXCR4 levels were detected using Western blots. Results were quantified against 1 μg of HeLa cells (positive controls). CXCR4 expression was defined as high (≥6-fold) or low (<6-fold). Primary endpoints were cancer recurrence and death. Statistical analysis performed included Kaplan-Meier survival analysis, log-rank test, and Cox proportional hazard model.ResultsAt a median follow-up of 37 mo, patients whose tumors had high CXCR4 overexpression (≥6-fold) had a significantly higher incidence of cancer recurrence (P = 0.014) and cancer-related death (P = 0.026) than those in the low CXCR4 group (<6-fold). After adjusting for tumor size and nodal status, the relative risk for cancer recurrence and death in the high CXCR4 group was 2.1-fold (P = 0.007; 95% CI: 1.22 to 3.8) and 2-fold (P = 0.047; 95% CI: 1.01 to 4.06) higher than those in the low CXCR4 group, respectively.ConclusionHigh CXCR4 overexpression in cancer specimens predicts a worse outcome in patients who have triple negative breast cancer.