Predictive experimental animal tumor models: a concept.

As an introduction to the session on Animal Tumor Models, a concept of animal model systems in presented that differentiates between models of organ-related diseases such as prostate or bladder cancer and models of a certain class of neoplasms found within a specific organ disease. Thus defined, no one animal tumor can completely represent and be predictive for a disease entity, no more so than can a single clinical experience with prostate cancer, e.g., be representative of all clinical cases. Rather, a block of animal tumors originating from a specific organ that reflects a spectrum of carefully defined growth patterns and reactivities best mimics the overall responses obtained clinically. Because immunotherapy is most logically visualized and applied in an adjuvant mode, its effectiveness as a therapeutic modality is vulnerable to the vagaries of individual tumor response to a primary modality. Therefore, the selection of appropriate tumor models for developmental studies in immunotherapy is critical, and the need for well-defined and characterized test systems in terms of chemotherapy and radiation responsiveness is emphasized.