Response rate accuracy in oncology - Analysis of causes for variation

We evaluated the impact of an evaluation committee (EC) on patients' overal l response status in a large multicenter trial in oncology. We identified r easons for disagreements between investigators and the EC. The Cancer Renal Cytokine (CRECY) study was a French multicenter trial that tested cytokine therapy in 489 patients with metastatic renal cell carcinoma. Objective re sponse (OR) evaluation included medical imaging and was studied according t o international guidelines. A blinded peer review of responders and litigio us cases was performed by an EC. Major disagreements occurred in 43% and mi nor disagreements in 10.5% of the reviewed files. The number of significant tumor responses was reduced by 23.2% after a review by the EC. Reasons for disagreements included errors in tumor measurements, errors in selection o f measurable targets, intercurrent diseases, and radiologic technical probl ems. These reasons for disagreements are all presumed responders by an EC. International guidelines for response evaluation should be updated by inclu ding more reliable methods of measurements and definition of minimal imagin g procedures.