CCR7 and CXCR4 as novel biomarkers predicting axillary lymph node metastasis in T1 breast cancer

Purpose: The chemokine receptors CCR7 and CXCR4 have been shown to play an important role in cancer metastasis. We therefore studied the differential expression of CCR7 and CXCR4, along with that of the biomarker HER2-neu, to evaluate whether these biomarkers could predict axillary lymph node metastasis in breast cancer. Experimental Design: Biomarker expression levels were evaluated using paraffin- embedded tissue sections of lymph node - negative (n = 99) and lymph node - positive (n = 98) T, breast cancer by immunohistochemical staining. Results: Lymph node - positive tumors showed higher rates of high cytoplasmic CCR7 staining (21.5% versus 8.5%, P = 0.013) and HER2-neu overexpression (21.5% versus 9.3%, P = 0.019) than did lymph node - negative tumors. Similarly, high cytoplasmic CXCR4 expression occurred more commonly in lymph node - positive tumors (11.2% versus 5.1 %, P = 0.113). In contrast, predominantly nuclear CXCR4 staining was more likely to be found in lymph node - negative tumors (54.5% versus 37.8%, P = 0.018). Furthermore, cytoplasmic CXCR4 coexpressed with HER2-neu was the only factor associated with involvement of four or more lymph nodes (16.7 % versus 1.2%, P = 0.04) among lymph node - positive tumors. When all three biomarkers (CCR7, CXCR4, HER2-neu) were utilized together, 50.0% of lymph node - positive tumors highly expressed one of these biomarkers compared with 18.8 % of the lymph node - negative tumors (P < 0.0001). Conclusions: Our results suggest that the chemokine receptor CCR7 is a novel biomarker that can predict lymph node metastases in breast cancer. Utilization of additional markers, such as CXCR4 and HER2-neu, further improves the prediction of the presence and extent of lymph node involvement.