CXCL12 expression is an adverse predictor for disease recurrence in patients with metastatic non-seminomatous testicular germ cell tumors

BACKGROUND: To validate the utility of the chemokine ligand 12 (CXCL12) as prognostic marker in patients with localized and metastatic germ cell tumors (GCT). METHODS: CXCL12 expression was analyzed on a tissue microarray consisting of 750 tissue cores of different histological tumor components, Germ cell neoplasia in situ (GCNIS) and adjacent normal tissue of 263 testicular cancer patients using a semi-quantitative score. The association between CXCL12 expression and recurrence-free survival (RFS) as well as overall survival (OS) was assessed using Kaplan-Meier curves with log-rank tests. RESULTS: CXCL12 expression was absent in all seminomas but was found in 52 of 99 (52.5%) non-seminomas. Follow-up was available for 260 patients of which 36 (13.8%) recurred. In patients with stage 1 non-seminoma GCT, CXCL12 expression was not associated with higher risk of disease recurrence (p = 0.270). In contrast, post chemotherapy RFS of patients with metastatic non-seminoma and positive CXCL12 expression was significantly shorter compared to CXCL12 negative patients (p = 0.003). OS differences were not statistically different between patients with CXCL12 positive or negative tumors for either localized or metastatic disease. CONCLUSIONS: CXCL12 is almost exclusively expressed in non-seminoma. Pure seminoma, GCNIS and adjacent normal testicular tissue are CXCL12 negative. Our analysis suggests that patients with metastatic disease and a CXCL12-positive non-seminoma are at higher risk for disease recurrence after first-line chemotherapy and might thus be candidates for more intensive treatment and/or closer follow-up.