The aim of this study was to investigate the predictive prognostic value of tumor metabolic activity measurements on serial 2-deoxy-2-[F] fluoroD-glucose (18F-FDG) positron emission tomography (PET/CT) scans to assess neoadjuvant chemoradiotherapy response in patients with locally advanced oesophageal cancer.
Forty five patients (63±7 yrs, 6 female) with advanced oesophageal cancer treated before surgery with concomitant chemoradiotherapy between 2006 and 2013 were followed-up for 24 ± 18 months (range 4-66). 18F-FDG PET/CT scans were obtained within one week before the start (PET1) and 1 month after the completion of the treatment (PET2). Tumour metabolitc activity was delineated measuring on the 18F-FDG scans the parameters: maximum standardized uptake value (SUVmax), SUV corrected for lean body mass (SUL) and total lesion glycolysis (TLG = total volume × SUVmean). Then, values for the parameters between PET1 and PET2 were calculated and expressed as % of PET1 measures.
At the moment of the analysis 25 patients were dead (Group1) and 20 alive (Group2). At univariate analysis of the PET/CT parameters, TLG at the end of the treatment, SUVmax, SUL and TLG resulted predictive of patients survival. At multivariate analysis, only TLG at the end of the treatment and TLG were significantly and independently associated with survival. ROC curve analysis showed a cut-off of 79498 for TLG as the optimal criterion to discriminate between Group1 and Group2 patients (AUC 0.81). ROC curves analysis resulted in -80% cut-off for TLG as the best to discriminate Group1 and Group2 patients (AUC 0.83). Using these cut-offs, log-rank analysis of the Kaplan–Meier method and Cox’s proportional hazards method confirmed the ability of TLG at the end of treatment [hazard ratio (HR), 0.30; 95% (CI), 0.13-0.66; P<0.005] and TLG [HR 0.39; 95% (CI), 0.17-0.87; P<0.04] to predict patients survival.
TLG is a promising predictive factor of outcome in patients with locally advanced oesophageal cancer undergoing neoadjuvant chemoradiotherapy with statistically higher prognostic power than other semiquantitative measures obtained in 18F-FDG scans.