Prognostic Significance of the Chemokine CXCL13 in Node-Negative Breast Cancer

615 Background: The chemokine CXCL13 is chemotactic for B cells. We examined the prognostic significance of CXCL13 mRNA expression in node-negative breast cancer. Methods: Microarray based gene-expression data for CXCL13 (205242_at) were analysed in four previously published cohorts (Mainz, Rotterdam, Transbig, Yu) of node-negative breast cancer patients not treated with adjuvant therapy (n=824). A meta-analysis of previously published cohorts was performed using a random effects model. Prognostic significance of CXCL13 on metastasis-free survival (MFS) was examined in the whole cohort and in different molecular subtypes (ER+/HER2-, ER-/HER2-, HER2+). Independent prognostic relevance was analysed using multivariate Cox regression. Results: Higher RNA expression of CXCL13 was related to better MFS in a meta-analysis of the whole cohort (HR 0.88, 95% CI 0.83-0.94, P<0.0001). Prognostic significance was most pronounced in the HER2+ positive molecular subtype (HR 0.72, 95% CI 0.59-0.87, P=0.0009) as compared to ER+/HER2- (HR 0.86, 95% CI 0.76-0.98, P=0.0024) and ER-/HER2- (HR 0.85, 95% CI 0.75-0.98), P=0.02) carcinomas of the breast. CXCL13 showed independent prognostic significance (HR 0.81, 95% CI 0.7336 0.8982, P=0.0001) in multivariate analysis. In addition to CXCL13, only histological grade of differentiation (HR 2.20, 95% CI 1.41-3.42, P=0.0005) and tumor size (HR 1.72, 95% CI 1.13-2.61, P=0.012), but neither age nor HER2 status nor hormone receptor status retained an independent prognostic association with MFS. Conclusions: The chemokine CXCL13 has independent prognostic significance in node-negative breast cancer. Higher expression of CXCL13 is associated with improved outcome.