A small number of participants on this study may need to have radiation therapy to help control the disease, as part of their routine care. This would only be done if the tumor(s) cannot be completely taken out with surgery, or if amputation is necessary but refused by the participant. If needed, and depending on where the tumor(s) are located, your doctor may decide that radiation is needed. All participants needing radiation or having surgery that the doctor considers as "incomplete" to control the disease are considered "higher risk" and will receive Regimen B therapy during and after radiation. (Radiation will usually begin during Weeks 12-14, but it could be anytime during ifosfamide therapy.) The radiation therapy will be explained to you in detail, and you will be asked to sign a separate consent form for it that will describe its risks.