- Any major surgery, radiotherapy, or immunotherapy within the last four weeks. Chemotherapy regimens with delayed toxicity within the last four weeks (six weeks for prior nitrosourea or mitomycin C). Chemotherapy regimens given continuously or on a weekly basis with limited potential for delayed toxicity within the last two weeks. Note: Use of erythropoietin replacement or bisphosphonates is considered supportive care and their use is permitted.