Comparison of Metabolic and Anatomic Response to Chemotherapy Based on PERCIST and RECIST in Patients with Advanced Stage Non-small Cell Lung Cancer

Background: The aim of this study was to explore the prognostic role of metabolic response to chemotherapy,determined by FDG-PET, in patients with metastatic non-small-cell lung cancer (NSCLC). Materials and
Methods:Thirty patients with metastatic NSCLC were analyzed for prognostic factors related to overall survival (OS) andprogression free survival (PFS). Disease evaluation was conducted with FDG-PET/CT and contrast-enhanced CTprior to and at the end of first-line chemotherapy. Response evaluation of 19 of 30 patients was also performedafter 2-3 cycles of chemotherapy. Morphological and metabolic responses were assessed according to RECISTand PERCIST, respectively.
Results: The median OS and PFS were 11 months and 6.2 months, respectively. Atthe end of first-line chemotherapy, 10 patients achieved metabolic and anatomic responses. Of the 19 patientswho had an interim response analysis after 2-3 cycles of chemotherapy, 3 achieved an anatomic response, while9 achieved a metabolic response. In univariate analyses, favorable prognostic factors for OS were number ofcycles of first-line chemotherapy, and achieving a response to chemotherapy at completion of therapy accordingto the PERCIST and RECIST. The OS of patients with a metabolic response after 2-3 cycles of chemotherapywas also significantly extended. Anatomic response at interim analysis did not predict OS, probably due to fewpatients with anatomic response. In multivariate analyses, metabolic response after completion of therapy wasan independent prognostic factor for OS.
Conclusions: Metabolic response is at least as effective as anatomicresponse in predicting survival. Metabolic response may be an earlier predictive factor for treatment responseand OS in NSCLC patients.