Use of 18F Fluorodeoxyglucose Positron Emission Tomography Computed Tomography in Assessing Response to Neoadjuvant Chemoradiation and Its Impact on Survival in Esophageal Squamous Cell Carcinoma.

Abstract

To determine the accuracy of 18F-Fluorodeoxyglucose positron emission tomography computed tomography (FDG-PET CT) in predicting response to neoadjuvant chemoradiation (NACRT) in esophageal squamous cell cancer (SCC) and impact of such response on survival. Retrospective analysis of patients with esophageal SCC (cT2-4N0-N+M0) who underwent PET CT before and 6weeks after NACRT followed by surgery was carried out in this study. Metabolic response was assessed by change in standardized uptake value (ΔSUVmax) after NACRT and the pathological response was graded. A receiver operating characteristic curve (ROC) was used to identify the optimal cut off value of SUVmax to predict histopathological response. The impact of metabolic response and pathological response on survival was determined. Of the 73 patients analyzed, 27 had complete metabolic response, while 24 had pathological complete response (PCR). However, only 14 of the 27 complete metabolic responders actually had PCR. At 67% ΔSUVmax, the optimum balance between sensitivity (70.83%) and specificity (69.23%) was achieved and the correlation between metabolic response and pathological complete response achieved statistical significance (p = 0.0009). However, ΔSUVmax of 67% was found to have no significant association with survival (p = 0.51). PCR was the only significant determinant of improved survival (p = 0.04). PCR which is a significant determinant of survival is not ideally predicted by ΔSUVmax on PET CT.