Pet models in cancer research: general principles.

Oncology has made great advancements in the past 50 years, moving from preliminary to complex studies and developing in the process numerous models. An important function in this development has been played by animal investigations that have displayed many aspects of cancer and led to the discovery of new therapies. Nevertheless, the debate about preclinical "tools" suited to predict efficacy as well as side effects of anticancer compounds and treatments is open. In this review we focus on the role of pet models in cancer research, whose continuously increasing importance is due to the disclosure of striking histopathological, anatomical, genetical, and biomolecular similarities among feline, canine, and human tumors. Remarkably, the improvement of clinical condition of companion animals, obtained by their enrolment in cancer trials, is generally perceived as an added value for the whole society. In the first paragraphs we examine crucial ethical, clinical, and financial issues that make up the framework of this area of translational research. Then we illustrate the new figures of researchers, namely experts in laboratory-clinic interface, who are needed in this field, and describe the relevant potentialities of pet cancer registries and genome projects. In the conclusions are summarized the principal arguments that support the adoption of pet models in tumor studies.