Prognostic significance of 18-FDG PET/CT and EUS-defined tumour characteristics in patients with oesophageal cancer

Aim: To determine the correlation between 2-[¹⁸F]-fluoro-2- deoxy-d-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) defined maximum standardized uptake value (SUV_max) and endoluminal ultrasound-defined tumour volume (EDTV) in patients with oesophageal cancer (OC) and their relative prognostic significance. Materials and methods: One hundred and eighty-five consecutive patients with OC were staged using CT, endoscopic ultrasound (EUS), and PET/CT. The maximum potential EDTV was calculated (πr²L, where r = tumour thickness and L = total length of disease including proximal and distal lymph node metastases). Primary outcome measure was survival from diagnosis. Results: Ninety-one percent of patients (168/185) had FDG-avid tumours on PET/CT. SUV_max correlated positively and significantly with EDTV (Spearman's rho = 0.339, p = 0.001). On univariate analysis, survival was inversely related to the PET/CT lymph node metastasis count (LNMC, p = 0.015), EUS N stage (p = 0.002), EDTV (<48 cm³, p = 0.001), EUS total length of disease (p = 0.001), SUV_max (p = 0.002), PET/CT N stage (p < 0.0001), and EUS LNMC (p < 0.0001). On multivariate analysis two factors were significantly and independently associated with survival: EDTV (HR, 3.118; 95% CI: 1.357-7.167; p = 0.007), and PET/CT N stage (HR, 0.496; 95% CI: 0.084-1.577; p = 0.022). Conclusion: EDTV and PET/CT N stage were important predictors of survival and further research is needed to identify critical prognostic values.