Combination Chemotherapy Followed by Bone Marrow and/or Peripheral Stem Cell Transplantation in Treating Patients With Recurrent Medulloblastoma or CNS Germ Cell Tumors

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so that they stop growing or die. bone marrow transplantation and peripheral stem cell transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of combination chemotherapy followed by bone marrow transplantation and/or peripheral stem cell transplantation in treating patients who have recurrent medulloblastoma or CNS germ cell tumors.