Clinical parameters for evaluating biological response modifier therapy.

Evaluating response in cancer is a well established practice, depending on the recognition of complete response, partial response, stable disease and progressive disease. For chemotherapeutic drugs, only those patients achieving a complete response experience an increase in survival. Partial response merely indicates that the drug has some activity in that disease. What the patient wants is not active drugs but prolonged survival with good quality of life. It is well recognised that tumours may remain dormant for many years, and that even those patients with complete responses to chemotherapy usually have minimal residual disease. It is assumed that such minimal disease is controlled and held in check by a biological process. The principal aim of biological response modifiers is to enhance this effect so as to control an even larger tumour load. It therefore follows that removal of all tumour is not the only benefit, and that stable disease and even slower progression might translate to longer survival. Survival curves are the acid test and we should expect longer survival even for those patients failing to achieve complete response if we are to establish that life imprisonment is as effective in cancer treatment as capital punishment.