Evaluation of Response to Stereotactic Body Radiation Therapy For Non-Small Cell Lung Cancer: PET Response Criteria in Solid Tumors (PERCIST) Versus Response Evaluation Criteria in Solid Tumors (RECIST)

Abstract Background: Recommendations for surveillance after stereotactic body radiation therapy (SBRT) for early stage non–small cell lung cancer (NSCLC) are not well defined. Recently, PET response criteria in solid tumors (PERCIST) have been proposed as a new standardized method to assess radiotherapeutic response both quantitatively and metabolically. The aim of this study was to evaluate therapeutic response following Stereotactic Body Radiotherapy in early-stage Non-Small Cell Lung Cancer patients by comparing PERCIST with the currently widely used RECIST.Methods: Forty-nine patients with early-stage Non-Small Cell Lung Cancer who had been prescribed Stereotactic Body Radiotherapy were studied. Responses of lesion were evaluated using CT and 18F-FDG PET according to the RECIST and PERCIST methods. PET-CT scans were obtained before SBRT and 3 to 6 months after SBRT. Associations between overall survival and clinicopathologic results (histology, tumor location, tumor size, lymphatic invasion, clinical stage, radiotherapeutic responses in RECIST and PERCIST) were statistically analyzed. Median patient follow-up was 30 months.Results: Thirteen patients had stage IA, 9 stage IB, 10 stage IIA, and 17 stage IIB biopsy-proven NSCLC. Three-year overall survival was 79.6%. CT scans indicated 3 regional recurrences. PET/d-chest indicated 3 regional recurrences and distant metastasis. Significant differences were observed in response classification between RECIST and PERCIST (Wilcoxon signed-rank test, P=0.0041). Uni-variate analysis showed that clinical stage, RECIST and PERCIST were significant factors associated with overall survival, whilst by multivariate analysis PERCIST was the only predictor of overall survival. SMD, PMD/PMR, CMR in PERCIST criteria was indicative of a 9.900-fold increase in the risk of overall survival in early NSCLC patients [RR 9.900 (95% CI 1.040, 21.591), P=0.001].Conclusion: RECIST based on the anatomic size reduction rate did not demonstrate correlation between radiotherapeutic response and prognosis in patients with early-stage NSCLC receiving SBRT. However, PERCIST was shown as the strongest independent predictor of outcomes. PERCIST might be considered more suitable for evaluation of NSCLC tumour response to SBRT than RECIST.