Response assessment in clinical trials: implications for sarcoma clinical trial design.

Response assessment and design of clinical trials require careful consideration of many factors, especially as validated response criteria can ultimately lead to the approval of an anticancer agent. Current anatomic imaging criteria are difficult to apply for evaluation of certain types of tumors, including soft tissue sarcomas. The emergence of new molecular imaging techniques, such as 64-slice computed tomography scanners and dynamic contrast magnetic resonance imaging, provide complementary information to conventional anatomical imaging. Currently the U.S. National Cancer Institute and the U.S. Food and Drug Administration are aiming to revise existing response criteria based on the development of volumetric anatomic imaging for oncology. Reviewing existing and new approaches in the design of clinical trials will help to optimize the clinical development and evaluation of new therapies for sarcomas.