Prediction of relapse in stage I testicular germ cell tumor patients on surveillance: investigation of biomarkers

BackgroundBetter biomarkers for assessing risk of relapse in stage I testicular germ cell tumor patients are needed, to complement classical histopathological variables. We aimed to assess the prognostic value of previously suggested biomarkers, related to proliferation (MIB-1 and TEX19) and to immune microenvironment (CXCL12, CXCR4, beta-catenin and MECA-79) in a surveillance cohort of stage I testicular germ cell tumor patients.MethodsA total of 70 patients were included. Survival analyses were performed, including Cox regression models.ResultsPatients with vascular invasion and elevated human chorionic gonadotropin levels showed significantly poorer relapse-free survival in multivariable analysis (hazard ratio=2.820, 95% confidence interval 1.257-6.328; hazard ratio=3.025, 95% confidence interval 1.345-6.808). Patients with no vascular invasion but with MIB-1 staining in >50% tumor cells showed significantly shorter relapse-free survival (p=0.042). TEX19 nuclear immunoexpression was confirmed in spermatogonial cells, and weak cytoplasmic immunoexpression was depicted in 15/70 tumors, not significantly impacting survival. CXCL12 immunoexpression in tumor cells did not associate with relapse, but non-seminoma patients exhibiting vascular invasion and CXCL12-positive stromal/inflammatory cells showed significantly improved relapse-free survival (p=0.015). Exclusively nuclear immunoexpression of CXCR4 associated with better relapse-free survival (p=0.032), but not after adjusting for vascular invasion. Patients with higher beta-catenin scores showed a tendency for poorer relapse-free survival (p=0.056). MECA-79 immunoexpression was absent.ConclusionsThe informative protein biomarkers (i.e., MIB-1, CXCL12, beta-catenin, and possibly CXCR4) may prove useful for risk-stratifying patients if validated in larger, multicentric and well-defined studies. Currently, classical histopathological features of testicular germ cell tumors remain key for relapse prediction.