The addition of chemotherapy as an effective means to treat cancer has had a major impact on selected human malignancies. Due to a general inability to dif ferentiate between normal and neoplastic cells, little selectivity exists in currently used oncolytic drugs. Consequently, significant toxicity to the patient is expected when systemic cancer chemotherapy is chosen as an appropriate therapeutic in tervention. Much of this toxicity, such as damage to the bone marrow, gastroin testinal tract, or hair follicles, is predictable based upon the fact that anticancer drugs kill actively dividing...