Intermediate prognosis in metastatic germ cell tumors (IPGCT): Outcome and prognostic factors.

Abstract

4560 Background: The IGCCCG classification published in 1997 is based on data from the 1970-80s. Approximately 25% of metastatic GCT patients belong to the intermediate prognosis category, that was associated with a 5-year overall survival (OS) rate of 79%. However, more recent data suggest significant changes. We have thus performed an international registry of IPGCT patients to analyze current treatment, outcome, and potential prognostic factors. Methods: Data of IPGCT patients, diagnosed between 1979-2012, were retrospectively collected from 14 centers. Treatment and outcome before and after implementation of IGCCCG were analyzed. For patients diagnosed since 1997 prognostic factors were investigated by uni- and multivariate analysis to test whether current patients or subgroups may require less intensive treatment. Results: This registry includes 637 patients: group 1 diagnosed prior 1997 (n = 237), and group 2 since 1997 (n = 400). Mean follow-up duration was 128.4 months (IQR: 168.9). Patients in group 1 and 2 received first-line treatment with BEP (median 4 cycles; range 1 - 6) in 98% and 97%, respectively. Response to chemotherapy (CR and marker negative PR) was similar: 91% group 1; 94% group 2; (p = 0.233), but survival curves were significantly superior in group 2 associated with a 5-year OS rate of 87% (group 2) and 81% (group 1), respectively (p = 0.011; 95%CI 294-317). Recurrence rates were higher in group 1 (36% versus 24%; p = 0.001). Patients treated with 3 cycles BEP (n = 58) in both groups had a similar outcome concerning OS compared to patients treated with 4 cycles (n = 489) (p = 0.415). Uni- and multivariate analysis revealed LDH levels < 2.0 UNL prior chemotherapy (p = 0.018; HR 0.35) and an adequate tumor marker decline at days 18-21 (half-life) of first cycle (p = 0.025; HR 2.58) as independent prognosticators, both associated with 5-year OS rates of 94%, respectively. Conclusions: Outcome of intermediate patients seems improved after implementation of the IGCCCG classification and less intensive regimes may also be sufficient. Here, patients treated with 3xBEP had a non-inferior outcome. A baseline LDH < 2.0 UNL and an adequate tumor marker decline after first treatment cycle can be used for further stratification.