Ga-68-Edotreotide Positron Emission Tomography/Computed Tomography Somatostatin Receptors Tumor Volume Predicts Outcome in Patients With Primary Gastroenteropancreatic Neuroendocrine Tumors

Abstract

Background We retrospectively aimed to assess the prognostic significance of somatostatin receptor (SSTR) standardized uptake value (SUVmax sstr ), SSTR representative tumor volume (RTV sstr ) and total lesion SSTR expression (TL sstr ) obtained by [ 68 Ga]Ga-edotreotide PET/CT ([ 68 Ga]Ga-SSTR PET/CT) in patients with primary gastroenteropancreatic neuroendocrine tumors (GEP-NET) before surgery. Material and Methods We analyzed patients who underwent [ 68 Ga]Ga-SSTR PET/CT 3-6 weeks before surgery from February 2020 to April 2022. The mean SUVmax sstr value, the RTV sstr (cm3; 42% threshold) and the TL sstr (g) were registered. Thereafter the patients were followed up 10.3 months (range 3-27). The PET/CT results were compared to the event free survival (EFS). Results Forty-two patients (61 ± 13 years) have been enrolled. At multivariate analysis only RTV sstr values were predictive. The Kaplan-Meier survival analysis for RTV sstr showed a significant better EFS in patients presenting lower values as compared to those having greater ( P = .003, log-rank test). SUVmax sstr was not suitable for predicting EFS, TL sstr mildly. Conclusion RTV sstr represents a valuable volumetric parameter able to predict the outcome in GEP-NET patients who underwent surgery. The magnitude of the SSTR representative tumor burden holds a predominant value for determining the response to therapy in GEP-NET patients before surgery, rather than the maximal SSTR representation at single voxel.