Use of 18F-FDG PET/CT to predict short-term outcomes early in the course of chemoradiotherapy in stage III adenocarcinoma of the lung.

The purpose of the present prospective study was to evaluate the use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the assessment of therapy response and the prediction of short-term outcomes by maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) following chemoradiotherapy (CRT) in patients with stage III adenocarcinoma of the lung. The study included a total of 15 patients, all of whom underwent two serial 18F-FDG PET/CT scans prior to and following 60-Gy radiotherapy with a concurrent cisplatin/pemetrexed combined chemotherapy regimen. SUVmax, SUVmean, MTV and TLG were determined. Short-term outcomes were assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST) and the PET Response Criteria in Solid Tumors (PERCIST). Post-CRT SUVmax, ΔSUVmax, ΔMTV and ΔTLG varied significantly between responders and non-responders (P=0.009, P=0.015, P=0.006 and P=0.004, respectively). The differences in SUVmax, SUVmean, carcinoembryonic antigen, MTV and TLG between the responders and the non-responders at the initial 18F-FDG PET/CT scans were not statistically significant (P>0.05). The overall response rate was significantly higher (P=0.01) when evaluated using PERCIST compared with evaluation using RECIST. It was concluded that post-CRT SUVmax, ΔSUVmax, ΔMTV and ΔTLG may be used to differentiate the responders from the non-responders following CRT for stage III adenocarcinoma of the lung. This would aid in deciding whether or not to increase dosages or to incorporate a boost treatment without the requirement to suspend therapy.