Baseline and interim [18F]FDG-PET/MRI to assess treatment response and survival in patients with M0 esophageal squamous cell carcinoma treated by curative-intent therapy

BACKGROUND: To investigate the value of [18F]FDG-PET/MRI in predicting treatment response and survival in patients with primary M0 esophageal squamous cell carcinoma. METHODS: Patients with esophageal squamous cell carcinoma received [18F]FDG-PET/MRI at baseline and during neoadjuvant or definitive chemoradiotherapy. The treatment response was classified according to the Response Evaluation Criteria for Solid Tumors 1.1. We used Kaplan-Meier and Cox regression analyses to assess the association between PET/MRI parameters and overall survival (OS) or progression-free survival (PFS). RESULTS: ) from baseline PET/MRI (area under the curve (AUC) = 0.688, P = 0.034) and total lesion glycolysis (TLG) from baseline PET/MRI (AUC = 0.723, P = 0.006) or interim PET/MRI (AUC = 0.853, P < 0.001) showed acceptable AUC for predicting treatment response. The TLG from interim PET/MRI (interim TLG, P < 0.001) and extracellular volume fraction (Ve) on interim PET/MRI (interim Ve, P = 0.001) were identified as independent prognostic factors for OS. Baseline Ve (P = 0.044) and interim TLG (P = 0.004) were significant predictors of PFS. The c-indices of the prognostic models combining interim TLG with Ve for predicting OS, and baseline Ve and interim TLG for predicting PFS were 0.784 and 0.699, respectively. These values were significantly higher than the corresponding c-indices of the TNM staging system (P = 0.002 and P = 0.047, respectively). CONCLUSIONS: Combining the baseline and interim [18F]FDG-PET/MRI qualitative imaging parameters aids in predicting the prognosis of patients with M0 esophageal squamous cell carcinoma. TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov (identifier: NCT05855291 and NCT05855278).