There are over 50 clinically approved anticancer drugs, as well as numerous steroidal agents, and in addition there are many new anticancer drugs in various stages of preclinical and clinical development. The anticancer drugs embody a diverse array of chemical structures. The purpose of this two volume publication is to provide a comprehensive review of the metabolism of anticancer drugs. The authors, each expert in their fields, have attempted to emphasize the relation of metabolism to the therapeutic and toxic effects of anticancer drugs, drawing whenever possible on human studies. There is a critical need for new approaches to treating cancer and it is certain that we will see an increasing number of new drugs with exotic chemical structures used for chemotherapy and perhaps chemoprevention. To understand the mechanisms of action of any drug it is important to know how the drug is transformed in the body, either into active metabolites or inactive products to be excreted. With this information the success or failure of a drug in arresting cancer cell growth can be assessed, and perhaps more effective drugs designed. Medical science has taken the first important steps toward controlling cancer. The use and study of current chemotherapeutic drugs has taught us much about how toxic chemicals can be employed to treat human cancer; comprehending the underlying metabolism of these drugs should facilitate even better modalities of treatment for the future.