Management of trials in the development of cancer chemotherapy.

Potential anti-cancer agents have classically undergone clinical assessment in Phase I, II and III trials. This paper examines the role of these trials and pre-clinical studies in the light of improving cancer chemotherapy. Many patients must now be treated with standard therapy before investigational drugs can be ethically used. The introduction of combined modality trials will require a very prolonged follow-up to demonstrate improved survival and recognize late onset of chronic toxicity.