Bone metastases in patients with relapsed/refractory germ cell tumors (GCT) undergoing first salvage chemotherapy: A retrospective analysis of a large international database.

4597 Background: Bone metastases (mets) are rare events in GCT patients (pts) and data on characteristics, risk factors, treatment and outcome in these pts are largely missing. Methods: A subgroup of 104 ptswith bone metsfrom the IPFSG database was analyzed. All patients experienced unequivocal relapse/progression after > 3 cycles of cisplatin-based chemotherapy and received conventional-dose (CDCT) or high-dose salvage chemotherapy (HDCT). Results: 104 / 1594 pts presented with bone mets (6,5%) at first relapse. Histology was pure seminoma in 26%, and non-seminoma in 74%. At initial diagnosis, 54% of pts had presented with "poor risk" according to IGCCCG. Overall response rate (ORR; CR+PR) to 1st-line chemotherapy was 89%. Median PFS after primary treatment was 3 months (range 0 - 140). Bone mets at first relapse were accompanied by abdominal, lung, mediastinal, liver and brain mets in 54%, 48%, 28%, 36%, and 14%, respectively. Tumor marker profiles were heterogeneous (elevation of AFP / s-HCG: 51% / 37%...