Irinotecan and Carboplatin as Upfront Window Therapy in Treating Patients With Newly Diagnosed Intermediate-Risk or High-Risk Rhabdomyosarcoma

INCLUSION CRITERIA: * Newly diagnosed, previously untreated histologically-proven rhabdomyosarcoma, undifferentiated sarcoma, or ectomesenchymoma. Histology must be confirmed by a MSKCC pathologist. Intermediate- or high-risk features as defined below: * All patients with Stage 4 tumors (distant metastases). Intermediate Risk: * All patients with non-metastatic undifferentiated sarcoma or alveolar RMS or ectomesenchymoma with alveolar features (regardless of age, site, size, stage, or degree of initial surgical resection); * All patients \< 1 year of age with non-metastatic embryonal RMS or ectomesenchymoma with embryonal features (regardless of site, stage, or degree of initial surgical resection). * Patients ≥ 1 year of age with Stage 2 or 3 (unfavorable site \[see Appendix I\] and either size \> 5 cm, OR regional nodes positive, or both), Group III (gross residual disease post-biopsy or attempted resection) embryonal RMS or ectomesenchymoma with embryonal features * Age: ≤ 50 years (inclusive) at the time of diagnosis. * Biopsy or definitive surgery within 42 days of start of treatment. Organ function: * Normal renal function: Normal serum creatinine for age or creatinine clearance or nuclear GFR of ≥ 80 ml/min/1.73m2 (in the absence of obstructive hydronephrosis, e.g., from pelvic or bladder/prostate tumor). * Normal liver function: Total bilirubin, SGOT/SGPT \< 2.5 times the upper limit of normal (in the absence of hepatic involvement by tumor) * Normal cardiac fu…