 - Patients who have had chemotherapy or radiotherapy within 4 weeks 6 weeks for nitrosoureas or mitomycin C prior to entering the study or those who have not recovered from adverse events AEs due to agents administered more than 3 weeks earlier; patients who have had prior pelvic radiation may be at increased risk for bowel perforation, and therefore may not have residual inflammatory disease of the bowel or residual bowel toxicity based on baseline imaging and clinical assessment; palliative limited-field radiation therapy is permitted, if all of the following criteria are met: 