Maintenance Oral Etoposide or Observation Following High-dose Chemo for GCT

This study is looking at whether taking a low-dose oral chemotherapy pill (etoposide) after completing high-dose chemotherapy for germ cell tumors (a type of cancer that usually starts in the testicles or ovaries) can prevent the cancer from coming back, compared to just being monitored. **You may be eligible if...** - You are 18 or older - You have non-seminomatous germ cell tumor (a specific type of testicular or ovarian cancer) - Your cancer came back after first-line chemotherapy - You completed high-dose chemotherapy treatment - Your tumor markers and scans show no active disease **You may NOT be eligible if...** - You have active cancer remaining after high-dose chemotherapy - You have severe organ damage from prior treatment - You are unable to take oral medications Talk to your doctor to see if this trial is right for you.