All patients, regardless of disease stage, are registered to this study and outcome is followed, although patients with metastatic RMS or non-RMS malignant mesenchymal tumors are referred for treatment on the SIOP-MMT-98 study. Patients diagnosed more than 8 weeks prior to entry or who are unavailable for follow-up are not treated on study. Doses are modified for patients under 1 year of age or under 10 kg of body weight. All other patients are assigned therapy based on risk group.