Accuracy of RECIST 1.1 for Non-small Cell Lung Cancer Treated with EGFR Tyrosine Kinase Inhibitors

Background: The Response Evaluation Criteria in Solid Tumors (RECIST) has been revised (RECIST 1.1) since initial publication of RECIST 1.0 in 2000. Major changes in RECIST 1.1 involve lymph node measurement, the maximum number of target lesions, and the definition of disease progression (PD). The purpose of this study was to evaluate the accuracy of RECIST 1.1 for non-small cell lung cancer (NSCLC) patients being treated with epidermal growth factor receptor tyrosine kinase inhibitors (TKIs).

Patients And Methods: We compared responses of 104 NSCLC patients treated with TKIs from eight prospective studies using RECIST 1.0 and 1.1.

Results: The short axis measurement for lymph nodes was the most influential change in RECIST 1.1 for the evaluation of response. Overall response rates (ORRs) using RECIST 1.0 and 1.1 were 35.6% and 38.5%, respectively. Under RECIST 1.1, six best responses were reclassified: two partial responses (PR) were re-categorized as complete responses, three cases of stable disease (SD) were reclassified as PR, and one case of SD was reclassified as PD. The progression-free survivals of three patients were extended. RECIST 1.1 showed a slightly increased ORR compared with RECIST 1.0.

Conclusion: RECIST 1.1 may reflect tumor burden more accurately than RECIST 1.0 in NSCLC patients treated with TKIs.