Abstract
BACKGROUND: Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) provides conventional response evaluation in solid tumors. However, RECIST 1.1 measures up to two lesions per organ, which can be time-consuming and less-reliable in terms of reproducibility. This study sought to compare response assessment using RECIST 1.1 and modified RECIST 1.1 (mRECIST 1.1, measuring the single largest lesion per organ) in advanced non-small cell lung cancer (NSCLC). METHODS: This study analyzed the medical files of 1,147 advanced NSCLC patients from the East Asia S-1 Trial in Lung Cancer (EAST-LC) clinical trial. The tumor responses were compared using the RECIST 1.1 and the mRECIST 1.1 by the kappa statistics. And a κ value of >0.75 indicated strong concordance. Concordance index (C-index), which ranges from 0-1, was calculated to evaluate prognostic accuracy of radiologic response according to the two criteria. The Kaplan-Meier method and log-rank test were conducted for survival. Statistical analyses were tested at a two-sided significance level of 0.05. RESULTS: The amount of target lesions was lower by mRECIST 1.1 than RECIST 1.1. The best tumor responses revealed a great concordance between two criteria (κ=0.989). The C-index by the two criteria was similar for overall survival (OS) (0.709 versus 0.708) and responders had significantly longer progression-free survival (PFS) and OS versus non-responders (P<0.001) by the RECIST 1.1 and mRECIST 1.1. The median OS using the original RECIST 1.1 criteria was 33.6 months in the complete response (CR) and partial response (PR) arm, 18.6 months in the stable disease (SD) arm, and 7.3 months in the progressive disease (PD) arm. When the mRECIST 1.1 criteria were applied, the median OS of the above three groups was 30.9, 18.3 and 7.3 months, respectively. Patients were also stratified into four groups using quartiles of the absolute PFS value according to the two criteria. In comparison with RECIST 1.1, the median OS were 5.8 versus 6.0 months, 8.3 versus 8.4 months, 14.5 versus 14.6 months, and 25.6 versus 25.6 months in the lowest quartile, 2(nd) quartile, 3(rd) quartile, and 4(th) quartile groups, respectively. CONCLUSIONS: mRECIST 1.1 was comparable to RECIST 1.1 and might be preferable owing to its convenience in the assessment of tumor response in advanced NSCLC.