Significance of mid-radiotherapy 18F-fluorodeoxyglucose positron emission tomography/computed tomography in esophageal cancer.

Abstract

Metabolic parameters evaluated by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) are known as prognostic markers in various cancers. We aimed to validate the predictive value of mid-radiotherapy (RT) FDG PET/CT parameters in esophageal cancer. Eighty-three patients treated with RT with or without chemotherapy between 2015 and 2020 were included. PET parameters including metabolic tumor volume (MTV), total lesion glycolysis, and mean (SUV_mean) and maximum standardized uptake value (SUV_max) were analyzed. Locoregional recurrence-free rate (LRFR) and distant metastasis-free rate (DMFR) were analyzed. The median follow-up period was 10.5 months. Mid-RT SUV_max was significantly associated with LRFR (HR 1.07, p = 0.009) and DMFR (HR 1.13, p = 0.047) while mid-RT MTV was associated with DMFR (HR 1.06, p = 0.007). Treatment response after RT was associated with overall survival (HR, 1.52, p = 0.025). Further, treatment response was significantly associated with mid-RT SUV_max. The optimal cutoff value for mid-RT SUV_max in predicting LRFR and DMFR was 11 while cutoff value for mid-RT MTV was 15. The patients with mid-RT SUV_max ≤ 11 showed superior LRFR and DMFR compared to SUV_max > 11 (1-year LRFR; 73.4% vs. 48.4%, p = 0.028, 1-year DMFR; 74.6% vs. 40.7%, p = 0.007). The 1-year DMFR was significantly different between patients with mid-RT MTV ≤ 15 and >15 (1-year DMFR; 78.2% vs. 31.9%, p = 0.002). Tumor metabolism changes during RT can be a useful predictive tool for treatment response and recurrence in patients with esophageal cancer. Clinicians may consider early response evaluation with PET during RT for predicting prognosis information about prognosis.