Asphericity as a measure of spatial heterogeneity predicts therapy outcome in FDG-PET of patients with esophageal carcinoma

Ziel/Aim It has been previously demonstrated that considering primary tumor asphericity (ASP) adds prognostic information to standard PET parameters in FDG-PET of patients with head and neck cancer. In the present study we address the question if ASP is also able to predict therapy outcome in patients with esophageal carcinoma.

Methodik/Methods FDG-PET/CT was performed in 139 consecutive patients ((62±10)y, 110 males) with newly diagnosed esophageal squamous cell carcinoma prior to definitive radiochemotherapy. In the PET images, the metabolic active volume (MTV) of the primary tumor was delineated with an adaptive threshold method. For the resulting ROIs, SUV_max and ASP were computed. Kaplan-Meier analysis and univariate Cox regression were performed with respect to overall survival (OS) and event-free survival (EFS) for the PET parameters and clinically relevant parameters. Additionally, a multivariate Cox regression including clinical parameters as confounding factors was performed.

Ergebnisse/Results Survival analysis revealed MTV and ASP as prognostic factors for OS and EFS (p  <  0.001). SUV_max was not prognostic for any of the clinical endpoints (p> 0.15). Among the clinical parameters, T-stage, N-stage, and UICC-stage were prognostic for OS and EFS (p = 0.001 - 0.02). In multivariate analysis both PET parameters (MTV and ASP) remained significant factors indicating their independent prognostic value.

Schlussfolgerungen/Conclusions In the investigated group of patients with esophageal carcinoma, ASP of the pretherapeutic FDG uptake pattern in the primary tumor is an independent prognostic factor for survival. Further investigations are necessary to confirm these preliminary results.