High-Dose Combination Chemotherapy and Radiation Therapy in Treating Patients With Newly Diagnosed Metastatic Rhabdomyosarcoma or Ectomesenchymoma

DISEASE CHARACTERISTICS: * Histologically confirmed high-risk rhabdomyosarcoma or ectomesenchymoma * Prior enrollment on COG-D9902 to confirm local histological diagnosis required * Tissue must be submitted for pathologic review within 2 days of patient registration on COG-D9902 * Newly diagnosed disease * Metastatic disease (stage IV, clinical group IV) * Has undergone initial surgical procedure (including biopsy) that provided the definitive diagnosis within the past 42 days * Parameningeal and paraspinal tumors allowed * Patients with parameningeal (without intracranial extension \[ICE\]) and paraspinal tumors should begin study chemotherapy at week 1 and radiotherapy at week 20 * Patients with evidence of ICE, as defined by contrast MRI showing that primary tumor touches, displaces, invades, distorts, or otherwise causes a signal abnormality of the dura in contiguity to the primary site in brain or spinal cord, are eligible * ICE is presumed to exist if the cerebrospinal fluid cytopathology is positive for tumor at diagnosis * Patients requiring emergency radiotherapy are eligible * Patients requiring emergency radiotherapy (for intracranial extension or spinal cord impingement) should begin study chemotherapy at week 1 (irinotecan hydrochloride and vincristine) concurrently with radiation therapy PATIENT CHARACTERISTICS: * ECOG or Zubrod performance status (PS) 0-2 (Lansky PS 50-100% for patients \< 10 years of age and Karnofsky PS 50-100% for pat…