[New guidelines to evaluate the response to treatment "RECIST"]

Response evaluation criteria in solid tumors (RECIST) guidelines proposes the simplification of response evaluation through the use of unidimensional measurements and the sum of the longest diameters for all target lesions. Data from collaborative studies, including more than 4,600 patients assessed for tumor response, support the simplification of response evaluation through the use of unidimensional measurements in stead of the conventional method using two measurements and the sum of the products. In this criteria, PR is at least a 30% decrease and PD is at least a 20% increase in the sum of the longest diameter of target lesions. In Japan, we will use this RECIST criteria for clinical studies of the new drug, because of international harmonization on new GCP. But, in this criteria, there are some problems in Japanese studies. One of them is that we cannot use the endoscopic findings for the evaluation of gastric cancer except for validation purposes, and one is that long NC (long SD) on breast cancer does not exist in this response criteria. We had discussed these problems at the 38th meeting of Japan Society of Clinical Oncology.