Prospective Observational Study of Outcomes After Gemcitabine, Docetaxel, Melphalan, and Carboplatin With Autologous Stem Cell Transplantation in Pediatric Relapsed/Refractory Germ Cell Tumors

Inclusion Criteria * Male or female participants, greater than 1 month of age up to 21 years old. Neonates (birth to 1 month of age) will not be enrolled on this protocol. * Participants with relapsed/refractory seminomatous or nonseminomatous GCT who undergo an autologous stem cell transplantation (ASCT) with conditioning therapy including gemcitabine, docetaxel, melphalan, carboplatin (GemDMC) for germ cell tumors * As part of our analysis, we will also include participants aged 0-21 years old who have previously underwent ASCT with GemDMC * Participants who receive the following regimen: High dose chemotherapy (HDC) course #1: Gemcitabine/Docetaxel/Melphalan/Carboplatin D-6 Admission and start hydration D-5 Gemcitabine 1,500 mg/m2 IV Docetaxel 275 mg/m2 IV D-4 Gemcitabine 1,500 mg/m2 IV Melphalan 20 mg/m2 IV Carboplatin 250 mg/m2 IV D-3 Gemcitabine 1,500 mg/m2 IV Melphalan 20 mg/m2 IV Carboplatin 250 mg/m2 IV D-2 Gemcitabine 1,500 mg/m2 IV Melphalan 20 mg/m2 IV Carboplatin 250 mg/m2 IV D-1 Rest D0 Stem Cell infusion Followed by HDC course #2 consisting of: High-dose course #2: Carboplatin/Etoposide D-6 Admission and start hydration D-5 to -3 Etoposide 750 mg/m2 IV Carboplatin 700 mg/m2 IV D-2 Rest D-1 Rest D0 Stem Cell infusion Exclusion Criteria * Participants who do not or did not receive GemDMC as part of the conditioning regimen for an ASCT are not eligible for this study