1201P - 18F-FDG-PET Response During the Second Week of Concurrent or Sequential Chemo-Radiotherapy Significantly Correlates with 2-Year Survival in NSCLC Patients

Abstract

ABSTRACT Purpose/Objective Assessment early during the course of treatment could identify prognostic groups, allowing treatment individualisation at a time when therapy changes are possible and before major toxicity occurred. We hypothesised that FDG-PET/CT imaging during the second week of chemo-radiotherapy would correlate with 2-year overall survival (OS). Methods We performed FDG-PET/CT imaging at two time points: One 4D PET/CT was performed prior to the start of radiotherapy, and a second 4D PET/CT during the second week of radiotherapy, sequential or concurrently with cisplatin-vinorelbine. In total 34 consecutive patients with NSCLC were successfully imaged. Images were analysed both for CT-based characteristics (volume of the primary tumour and, if present, involved lymph nodes), PET characteristics included the average, maximum and peak SUV (SUVmean, SUVmax, SUVpeak, resp.). The difference in these parameters between both time points were correlated to the 2-year overall survival. Results The change in FDG-uptake (SUVmean) of the primary tumour was significantly different (p = 0.007) between the group surviving more than 2 years (-20.2 ± 20.5%) compared to the group not surviving two years ( + 2.1 ± 21.9%). Using the EORTC criteria for partial response (decrease in signal of 15%), a sensitivity of 63% and a specificity of 93% in this population was found that separated the survival curves (p = 0.001). CT-based early response parameters were not associated with prediction of survival. Conclusions Decrease in FDG-uptake already in the second week of (chemo-) radiotherapy is correlated with overall survival in NSCLC. This opens avenues for individualized and optimized treatment based on early treatment response analysis. A prospective trial including 120 patients has just been terminated. Disclosure All authors have declared no conflicts of interest.