SARC-CTOS imaging symposium: introduction to the problem from a clinical perspective.

Failure to correctly design clinical trials precludes effective evaluation of yield data. For instance, the Response Evaluation Criteria in Solid Tumors were developed using unidimensional measurements, while the World Health Organization criteria were based on bidimensional measurements. Attempts to compare data from the two response criteria have been problematic. There is an ongoing debate regarding the definition of what constitutes response, and there is a need to update the existing criteria. Advances in imaging techniques need to be evaluated and added into new response criteria. As sarcoma patients can derive clinical benefit from therapy without sizable tumor shrinkage, identifying other qualitative changes, such as ossification of osteosarcomas, should also be incorporated into new response criteria. This article reviews existing approaches to assess response criteria in sarcomas, and explores the role of modern imaging in the evaluation of clinical benefit.