Comparison of RECIST 1.0 and RECIST 1.1 on Computed Tomography in Patients with Metastatic Colorectal Cancer

Abstract

Objective: We conducted this study to compare tumor measurement by computed tomography (CT) and tumor response assessment between Response Evaluation Criteria In Solid Tumors (RECIST) 1.0 and RECIST 1.1 in patients with metastatic colorectal cancer (CRC). Methods: We reviewed the medical records of patients with metastatic CRC who received first-line chemotherapy between January 2004 and December 2012 and compared CT tumor measurement using two RECIST versions. Results: A total of 58 patients who had target lesions according to RECIST 1.0 were included in the study. The number of target lesions recorded by RECIST 1.1 was significantly lower than that by RECIST 1.0, with a decrease experienced in 48 patients (82.7%). Six patients had no target lesions because of the new criteria of RECIST 1.1 for lymph node size. Out of 95 lymph nodes from 58 patients, only 40% were defined as target lesions according to RECIST 1.1. The overall response rate of first-line chemotherapy according to RECIST 1.0 and 1.1 was 41.5 and 40.4%, respectively. The best tumor responses showed almost perfect agreement between RECIST 1.1 and RECIST 1.0 (ĸ = 0.913). Three patients showed disagreement of the best responses between the two RECIST versions. Conclusion: RECIST 1.1 showed a highly concordant response assessment with RECIST 1.0 in metastatic CRC and its clinical impact on therapeutic decisions was minimal.