P2.02-045 Prognostic Value of Metabolic FDG-PET Response in Locally Advanced NSCLC: A Literature Review

Abstract

It is still a matter of debate whether metrics of metabolic imaging by 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) predict clinical outcome in non-small cell lung cancer (NSCLC). Pretreatment FDG uptake in the primary tumor has been shown to be a prognostic factor for survival. The prognostic role of FDG-PET in the evaluation of tumor response remains unclear and controversial. Hence, we conducted a comprehensive literature review to assess the prognostic value of FDG-PET/CT response monitoring along multimodality treatment in patients with locally advanced NSCLC. A systematic search of studies published in PubMed was performed using the keywords “positron emission tomography” or “PET”, “non-small cell lung cancer,” and “response” or “outcome.” References from adequate articles were checked for studies not retrieved by the search strategy. Inclusion criteria were: studies limited to locally advanced NSCLC containing >60% stage III patients, studies in which response monitoring with FDG-PET or PET/CT was performed, and studies that reported survival data. Twenty-two studies (median 47 patients, range 15-545) published between 1998 and 2016 were included in the analysis. Ten studies used PET alone while recent trials used integrated PET/CT. PET based response evaluation was performed either after neoadjuvant chemotherapy prior to surgery or radiotherapy either after radical treatment consisting of (chemo)radiotherapy. Eight studies specifically addressed the prognostic value of early metabolic response measurement, either during induction chemo(radio)therapy (n=2) either early in the course of radical (chemo)radiotherapy (n=6). A heterogeneity between the studies was observed regarding timing of the repeat PET, thresholds to define metabolic response, and metrics of metabolic FDG imaging such as MRglu (metabolic rate of glucose), Total Lesion Glycolysis (TLG), Standardized Uptake Value (SUV), SUVmax, SUVpeak, SUVmean or Metabolic Tumor Volume (MTV). All studies showed a significant correlation between either the change in FDG uptake or the residual FDG uptake within the primary tumor and survival. Posttreatment FDG-PET/CT has been considered as a useful tool in determining prognosis and guiding therapy for patients with locally advanced NSCLC. Before implementation in routine clinical practice, there is however a need for standardization of PET data acquisition and analysis and a validation of a single definition for metabolic tumor response.