**6. Summary**

The era of molecular biology have created great expectations on our ability to translate these discoveries into effective treatments for patients. Over the last decade, there has been an in‐ creasing knowledge about pathophysiological processes that are common to most tumors including: independence from growth signals, insensitivity to growth-inhibitory signals, evasion of apoptosis, limitless potential for replication, sustained angiogenesis, and tissue invasion and metastasis. These major pathways deregulated in cancer have a key role in tu‐ mor development and microenvironment. These features have enabled the emergence of a wide spectrum of novel oncologic drugs that are designed to target and interfere with spe‐ cific aberrant biological pathways. In general, these agents use different strategies to inter‐ fere with specific biological targets, such as blocking growth factors, receptors, or tyrosine kinase (TK) action.

The use of new drugs in the treatment of advanced or metastatic kidney cancer, with differ‐ ent mechanisms of action compared to conventional chemotherapy raises new questions. One of the biggest problems with new drugs are produced in the evaluation of the response, and the incorporation of new imaging techniques (MRI diffusion, perfusion CT, nuclear medicine, etc....) in the diagnosis of extension and assessment of efficacy.

In this chapter we have reviewed the main techniques of radiological diagnosis and staging, the value of new imaging modalities, and discuss the validity of the classical criteria of inter‐ pretation of response.
