Maximum Standardized Uptake Value in Lymph Nodes Measured by 18F-FDG PET/CT Predicts the Outcome of Patients with Oesophagus Squamous Cell Carcinoma

Background: To investigate the prognostic value of 18F–fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in esophagus squamous cell carcinoma (ESCC), PET/CT imaging characteristics were explored in the present study.Methods: Baseline PET/CT and clinical characteristics were collected in 125 patients with ESCC treated with radical radiotherapy from 2007–2016. The maximum standardized uptake value (SUVmax) of the primary gross tumour (SUVmax-T) and metastatic lymph node (SUVmax-N) were separately measured using X-tile. Overall survival (OS) and progression free survival (PFS) were estimated according to the Kaplan–Meier method. A multivariate Cox model was used to establish the independent prognostic factors.Results: The gross tumours presented higher 18F-FDG uptake than normal tissues with a median SUVmax-T of 12.5. The OS and PFS did not show significant differences between patients with SUVmax-T ≥ 12.5 and those with SUVmax-T <12.5 (P>0.05). However, patients with SUVmax-N ≥ 11 had a significantly worse OS and PFS than those with SUVmax-N <11 (P<0.05). A weak correlation was observed in SUVmax-T and SUVmax-N. The OS and PFS of patients with PET-negative LNs was significantly better than those with PET-positive LNs. However, the OS and PFS of patients with one or two PET-positive LNs were not significantly better than those with more than two PET-positive LNs. In the univariate analysis, cT stage, positive or negative lymph nodes on the PET-CT image and the SUVmax-N were established as significant prognostic factors for both OS and PFS. In multivariate analysis, SUVmax-N was proved to be an independent predictor for OS and PFS.Conclusions: SUVmax-N, but not SUVmax-T, is an independent prognostic indicator for patients with ESCC.