- If > 21 years old - extensive prior therapy including > 12 months of any alkylator chemotherapy (etoposide >100 mg/m^2 x 5 days, cyclophosphamide >1 gm/m^2 or mitoxantrone >8 gm/m^2) delivered at 3-4 week intervals or > 6 months alkylator therapy (as above) with extensive radiation (determined by Radiation Oncology, e.g. mantle irradiation for Hodgkin's) and/or prior radiation therapy that makes a patient ineligible for TBI.