Does serum tumor marker half-life complement pretreatment risk stratification in metastatic nonseminomatous germ cell tumors?

The goal of this study was to determine whether the serum tumor marker half-life (MHL) of human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP) during initial chemotherapy can complement pretreatment risk stratification in metastatic nonseminomatous germ cell tumors. One hundred forty-seven patients were assessable for MHL during the first two cycles of platinum-based chemotherapy. MHL calculation was based on two consecutive values using Kohn's apparent half-life formula (MHL =ln 1/2/G, where G was the gradient of the marker slope) or on three (or more) values using simple linear regression. MHL was regarded as prolonged if it was more than 3.5 days for HCG or more than 7 days for AFP. The median MHL for HCG was 2.8 days (range, 0.7-16.7) and for AFP was 6.2 days (range, 2. 6-65.4). Thirty-five of 108 patients (32%) had a prolonged MHL for HCG, 41 of 114 (36%) had a prolonged MHL for AFP, and in 59 of 147 patients (40%), either or both MHLs were prolonged. If patients with both MHLs normal were compared against patients with either or both MHLs prolonged, highly significant differences in progression-free survival (P < 0.0001) and overall survival (P = 0.0005) were demonstrated. The test accuracy was 70% for both progression-free and overall survival, and it was slightly greater than the overall predictive value of the Medical Research Council prognostic classification. A combination of Medical Research Council criteria and MHL analysis allowed us to refine prognostic assessment. Because MHL analysis is able to complement pretreatment risk stratification and can support selection of patients for early-dose intensified chemotherapy, it should be included in prospective clinical trials for patients with poor-prognosis disease.