The impact of large lesions on the RECIST assessment criteria

17560 Background: Since 2000 the Response Evaluation Criteria in Solid Tumors (RECIST) has been the standard measurement criteria for calculating tumor response. Although RECIST includes a minimun target lesion size to minimize errors in estimating the change in size of small lesions, RECIST does not provide a maximum size for target lesion selection. Previous research has shown that a tumor's rate of growth decreases at is approaches maximum volume. Furthermore, large lesions have the ability to greatly impact the overall assessment, which could result in the misclassification of response. The purpose of this study was to determine if the inclusion of a maximum target lesion size in the RECIST guidelines would significantly impact the response assessment. Methods: We reviewed 29 patients from the Tumor Imaging Metrics Core (TIMC) database who had 1 or more lesions > 7 cm at baseline and had a minimum of 3 time points. Previous research has shown that as a tumor approaches its maximum size its growth rate...