New Response Evaluation Criteria in Solid Tumors (RECIST) guidelines for advanced non-small cell lung cancer: comparison with original RECIST and impact on assessment of tumor response to targeted therapy

Abstract

Objective: The purpose of this article is to compare the recently published revised Response Evaluation Criteria in Solid Tumors (RECIST) guidelines (version 1.1) to the original guidelines (RECIST 1.0) for advanced non-small cell lung cancer (NSCLC) after erlotinib therapy and to evaluate the impact of the new CT tumor measurement guideline on response assessment.

Materials and methods: Forty-three chemotherapy-naive patients with advanced NSCLC treated with erlotinib in a single-arm phase 2 multicenter open-label clinical trial were retrospectively studied. CT tumor measurement records using RECIST 1.0 that were generated as part of the prospective clinical trial were reviewed. A second set of CT tumor measurements was generated from the records to meet RECIST 1.1 guidelines. The number of target lesions, best response, and time to progression were compared between RECIST 1.1 and RECIST 1.0.

Results: The number of target lesions according to RECIST 1.1 decreased in 22 patients (51%) and did not change in 21 patients (49%) compared with the number according to RECIST 1.0 (p < 0.0001, paired Student's t test). Almost perfect agreement was observed between best responses using RECIST 1.1 and RECIST 1.0 (weighted kappa = 0.905). Two patients with stable disease according to RECIST 1.0 had progressive disease according to RECIST 1.1 criteria because of new lesions found on PET/CT. There was no significant difference in time to progression between RECIST 1.1 and RECIST 1.0 (p = 1.000, sign test).

Conclusion: RECIST 1.1 provided almost perfect agreement in response assessment after erlotinib therapy compared with RECIST 1.0. Assessment with PET/CT was a major factor that influenced the difference in best response assessment between RECIST 1.1 and RECIST 1.0.

Fig. 1

Number of target lesions according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 versus that according to RECIST 1.0. Number of target lesions calculated using RECIST 1.1 was significantly lower than that calculated using RECIST 1.0 (p < 0.0001, paired Student’s t test).

Fig. 2

Comparison of diameters of target lesions by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and 1.0. A, Comparison of sum of longest diameters of target lesions on baseline CT measurements by RECIST 1.1 and RECIST 1.0 showed high correlation between two CT measurements (r = 0.936 and r² = 0.8758, Pearson’s correlation). B, Decrease in sum of longest diameters of target lesions on baseline CT measurements by RECIST 1.1 (B1.1) compared with baseline CT measurement RECIST 1.0 (B1.0) (p = 0.0001, paired Student’s t test).

Fig. 3

Percentage changes in sum of long diameter CT measurements by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 versus RECIST 1.0 at every two cycles of therapy. High correlation in percentage changes and high concordance of response assessments were observed between CT measurements by RECIST 1.1 and by RECIST 1.0. (r = 0.986 and r² = 0.972 at cycle 2 [n = 28]; r = 0.998 and r² = 0.996 at cycle 4 [n = 7]; r = 0.657 and r² = 0.432 at cycle 6 [n = 5]; r = 0.949 and r² = 0.901 at cycle 8 [n = 4]; r = not applicable and r² = not applicable at cycle 10 [n = 1]; and r = 0.979 and r² = 0.959 at cycles 2–10 [n = 45], Pearson’s correlation). PD = progressive disease, PR = partial response, SD = stable disease.

Fig. 4

Percentage changes in sum of longest diameter CT measurements by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and RECIST 1.0 after first two cycles of therapy. Response assessments of target lesions at first two cycles of therapy by RECIST 1.1 and RECIST 1.0 were concordant in 27 (96%) of 28 patients and discordant in one patient (4%; asterisk). PD = progressive disease, PR = partial response, and SD = stable disease.

Fig. 5

Time to progression by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 versus RECIST 1.0. Difference in time to progression was not significant (p = 1.000, sign test).

Fig. 6

Comparison of sum of longest diameters of target lesions on baseline CT measurements performed in clinical trial (measurement 1) and by observer in present study (measurement 2). A and B, High correlation was noted between two measurements for both Response Evaluation Criteria in Solid Tumors (RECIST) 1.0 (A) and RECIST 1.1 (B) (r² = 0.9740 and r² = 0.9846, respectively; Pearson’s correlation). C and D, Bland-Altman plots of two sets of baseline CT measurements for RECIST 1.0 (C) and RECIST 1.1 (D) are shown. Interobserver variability is shown as function of mean of two measurements. Dotted lines indicate upper and lower 95% limits of agreement. Dashed lines indicate mean relative difference.