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

Background To determine the accuracy of F-18-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. Methods Retrospective analysis of patients with esophageal SCC (cT2-4N0-N+M0) who underwent PET CT before and 6 weeks after NACRT followed by surgery was carried out in this study. Metabolic response was assessed by change in standardized uptake value (Delta SUVmax) 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. Results 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% Delta SUVmax, 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, Delta SUVmax 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). Conclusion PCR which is a significant determinant of survival is not ideally predicted by Delta SUVmax on PET CT.