Radiological evaluation of response to chemotherapy can be carried out by applying the RECIST (Response Evaluation Criteria in Solid Tumors) criteria, currently considered the most objective method for monitoring lesions. Aimed at finding a general response curve, 21 patients with lung and kidney tumors, as well as colorectal carcinoma were studied between 2006 and 2008. Statistical proceedings included variance (ANOVA), co-variance (ANCOVA) and logarithmic regression analysis. Target-lesion size reduction, duration of response and overall response of different types of tumors did not differ significantly. A general response curve was obtained: log (RRi)= 1,897-0,028 t, where RRi is the relative RECIST count, and t is time (expressed in months). As an expected outcome –because of variety of drugs, type of tumors and variability rates in individual response– the determination coefficient in regression was 10.9%. However, it constitutes a first approach to solid tumors response and proves the accuracy and usefulness of RECIST methodology.
