Comparison of RECIST and PERCIST for evaluation of response to concurrent chemo-radiotherapy in patients with nasopharyngeal carcinoma

Objectives: To compare the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and Positron Emission Tomography Response Criteria In Solid Tumors (PERCIST) 1.0 using PET volume computer-assisted reading (PET VCAR) for response evaluation in patients with locoregional advanced nasopharyngeal carcinoma (NPC) treated with concurrent chemo-radiotherapy (CCRT).

Methods: A total of 36 patients with NPC who received standard CCRT were included in the prospective study. Before and after 3 months of treatment, all of the participants underwent head and neck MR and ¹⁸F-FDG PET/CT for the assessment of therapeutic response. All of the scans were performed within 1 wk. With the assistance of PET VCAR, the CCRT responses were evaluated according to the RECIST 1.1 and PERCIST 1.0. Concordance among these criteria was assessed using Cohen’s κ coefficient and the Wilcoxon signed-rank test. Progression-free survival (PFS) was calculated using the Kaplan-Meier test. Multivariate analysis was performed to identify the prognostic factors influencing PFS using Cox proportional hazards regression model.

Results: According to RECIST 1.1, 15 patients showing complete response (CR), 19 partial remission (PR), 2 stable disease (SD) and 0 progressive disease (PD). According to PERCIST 1.0, 19 patients showing complete metabolic response (CMR), 14 partial metabolic remission (PMR), 2 stable metabolic disease (SMD) and 1 progressive metabolic disease (PMD). RECIST 1.1 and PERCIST 1.0 response classifications were discordant in 9 patients (25.0%), resulting in moderate concordance (κ=0.562, P=0.469). Patients with a CR according to RECIST 1.1 had significantly longer PFS (P<0.001) than patients with non-responders (SD and PD), but not significantly longer than patients with PR (P=0.937). According to PERCIST 1.0, patients with a CMR had a significantly longer PFS than those with PMR and those with non-responders (SMD and PMD) (P=0.022 and P<0.001, respectively). Multivariate analysis showed that only PERCIST 1.0 was the significant prognostic factor for PFS (HR=11.813, P=0.02).

Conclusion: RECIST 1.1 and PERCIST 1.0 have moderate concordance for the detection of response to CCRT in patients with NPC at 3 months after treatment. However, PERCIST 1.0 is found to be the significant prognostic predictor of outcomes and might be considered more suitable for evaluation of CCRT response to NPC than RECIST 1.1. Research Support: No