To Compare and Determine the Diagnostic Accuracy of [(18)F]-fluorodeoxyglucose Positron Emission Tomography Scan in Predicting Pathological Response in Operated Carcinoma Esophagus Patients after Initial Neoadjuvant Chemoradiation and Neoadjuvant Chemotherapy

The objective of this study was to determine whether [(18)F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) scan could predict the pathological response in esophageal carcinoma after surgery in patients receiving neoadjuvant concurrent chemoradiation (NACCRT) and neoadjuvant chemotherapy (NACT). A randomized prospective study was carried out from March 2014 to October 2016; thirty patients of histopathologically proven, locally advanced, potentially operable carcinoma esophagus comprising both squamous carcinoma and adenocarcinoma were randomized into NACCRT and NACT arms equally. Both groups had pretreatment FDG-PET-computed tomography (CT) scan and repeat scan after 5–6 weeks of neoadjuvant therapy (NAT). The change in mean %Δmaximum standardized uptake value (%ΔSUVmax) was compared with tumor regression grade (TRG) in the postoperative histology. Patients with TRG 1–2 were deemed responders and 3–5 were nonresponders. Pathologic response was correlated with percentage change in [(18)F]-FDG uptake (%ΔSUVmax); receiver operating characteristics (ROC) analyses were done to assess sensitivity and specificity of FDG-PET to determine its diagnostic accuracy. The mean SUV in NACCRT group decreased from 15.47 ± 2.92 to 7.31 ± 4.07 (P < 0.001), while in NACT group, mean SUV decreased from 14.74 ± 3.95 to 8.60 ± 3.89 (P < 0.001). Comparison between NACCRT and NACT leads to mean SUV of 57.80 ± 22.40 and 45.92 ± 19.23, respectively (P = 0.13). In NACCRT and NACT, TRG had mean %ΔSUVmax values of 2.53 ± 1.25 and 2.93 ± 1.28 (P = 0.393). However, we found a statistically significant correlation between SUV% reduction and TRG (P = 0.002). ROC curve analysis for FDG-PET-CT suggested an area under the curve of 0.693 and sensitivity and specificity of 80% and 46.7%, respectively. NACCRT and NACT lead to a statistically significant reduction in mean %ΔSUVmax and with statistical significance correlation when compared with pathological response assessment. Hence, PET-CT can be used for differentiating responders and nonresponders to NAT.