3.113 Prior radiation therapy allowed to <25% of the bone marrow (see Protocol Appendix VII, Distribution of Active Bone Marrow in the Adult), and patients must have recovered from the toxic effects of the treatment prior to study enrollment (except for alopecia). Patients are allowed to have received standard postoperative adjuvant radiation therapy for rectal cancer. Prior radiotherapy must be completed < 30 days before study entry. Lesions that have been radiated in the advanced setting cannot be included as sites of measurable disease unless clear tumor progression has been documented in these lesions since the end of radiation therapy.