Is serum tumor marker half-life a guide to prognosis in metastatic nonseminomatous germ cell tumors?

BACKGROUND: The value of serum tumor marker kinetics of AFP and HCG assessed by marker half-life (MHL) analysis for diagnosis and in the follow-up of patients with nonseminomatous germ cell tumors (NSGCT) is still debated controversally. The aim of this retrospective study was therefore to investigate the influence of serum MHL during the first two cycles of chemotherapy on the long-term outcome in metastatic NSGCT.

MATERIAL AND METHODS: 147 patients with at least 2 abnormal marker values > 7 days after start of chemotherapy were investigated for HL analysis (HL cut off 3.5 days for HCG and 7 days for AFP). HCG and AFP determinations were performed by a double monoclonal IRMA (HCG) and conventional RIA (AFP) developed by our laboratory.

RESULTS: According to these cut offs 35/108 patients (32.4%) had a prolonged HCG HL and 41/114 patients (36%) a prolonged AFP HL. Patients with either MHL prolonged had a significantly inferior overall survival (OS; 10 year OS 37% vs. 75%, p = 0.0005) and progression-free survival (PFS; 10 year PFS 29% vs. 69%, p < 0.0001) than those with a prolonged HCG MHL (OS; 10 year OS 36% vs. 65%, p = 0.003; 10 year PFS 28% vs. 56%; p = 0.001) and even more than those with a prolonged AFP MHL (10 year OS 39% vs. 70%, p = 0.02; 10 year PFS 32% vs. 56%, p = 0.01).

CONCLUSION: The remarkable prognostic information assessed by MHL analysis in this retrospective study merits further confirmation by a prospective study for its appropriateness in selecting patients for high dose chemotherapy.