Prognostic value of functional tumor burden on 68Ga-DOTATOC PET/CT in patients with pancreatic neuro-endocrine tumors

Abstract

Despite their relative quiescence, pancreatic neuro-endocrine tumors (pNET) can correspond to various presentations and outcomes. Several prognostic factors have been identified, including maximal standardized uptake value of the most intense focus (maxSUVmax) on Positron Emission Tomography (PET) with a somatostatin analogue. Herein, we investigate the prognostic value on progression free-survival of the total functional tumor volume (TFTV) measured by 68 Ga-DOTATOC PET. From patients who underwent 68 Ga-DOTATOC PET from 2008 to 2014, we selected consecutive patients with G1 or G2 pNET (2010 World Health Organization classification), at least one abnormal focus on PET and available follow-up data. TFTV was computed by summing the volumes of all pathological foci, delineated use of 41% of its SUVmax for each threshold focus. Fifty patients were included. During the follow-up period, 33 patients had stable or responsive disease (66%; median duration 28.5 months; range 6.3-77.7 months) and 17 patients experienced disease progression (34%; median progression time 21 months; range 6.7-44.7 months). Median PFS was 43.5 months. The best TFTV cut-off for predicting progression within 24 months was 13.8 cm 3 . Multivariate analysis determined that TFTV greater than 13.8 cm 3 was the only criterion considered a significant risk factor for tumor progression (HR 2.9; p=0.0003). A significant difference in PFS was observed for TFTV (<13.8 vs. ≥ 13.8 cm 3 : median not reached vs. 25 months; p=0.0001).Our study suggests that 68Ga-DOTATOC TFTV measured on PET images is a valuable prognostic biomarker in patients with well-differentiated pNETs of all stages.

Semiautomatic Tumor Delineation for Evaluation of 64Cu-DOTATATE PET/CT in Patients with Neuroendocrine Neoplasms: Prognostication Based on Lowest Lesion Uptake and Total Tumor Volume

“…We therefore employed a standardized patient-specific cutoff to delineated lesions based on the method described for 18 F-FDG (19). Recently, a number of papers have described the prognostic implications of tumor volume derived from 68 Ga-DOTATATE (10-12) or 68 Ga-DOTATOC (13,14), but not for 64 Cu-DOTATATE. In order to obtain tumor volume, different strategies were utilized; manual delineation of lesions including areas with either 41% or 50% of lesion SUVmax or semi-automatic delineation with individual SUVmax threshold based on agreement between anatomical and functional lesion delineation.…”

“…In order to obtain tumor volume, different strategies were utilized; manual delineation of lesions including areas with either 41% or 50% of lesion SUVmax or semi-automatic delineation with individual SUVmax threshold based on agreement between anatomical and functional lesion delineation. However, none of the studies reported time spent on segmentation of tumors (8)(9)(10)(11)(12)(13)(14). In the present study, the time spent was approximately 20 minutes per patient, although less time (down to 5 minutes) was needed when areas of physiological uptake (kidney, urinary bladder and spleen) could be avoided due to tumor location.…”

“…For 18 F-FDG PET both metabolic tumor volume and total lesion glycolysis have been reported (7)(8)(9), which has also been adopted to SRI (10). Total tumor volume based on SRI tumor segmentation has been shown to have prognostic implications (11)(12)(13)(14). Besides volumetric information, lowest lesion SUVmean would also be available with total tumor segmentation and thus the most dedifferentiated lesion could be used for prognostication.…”

Prognostic Value of Volume-Based Parameters Measured by SSTR PET/CT in Neuroendocrine Tumors: A Systematic Review and Meta-Analysis

“…A total of eight studies involving 593 patients were included in our meta-analysis. Five studies (21,22,(28)(29)(30) were retrospective and three studies (31)(32)(33) were a prospective design. According to the WHO grade, three researches (22,29,30) included well-differentiated NETs (grade 1 and/or 2).…”

(Radio)Theranostic Patient Management in Oncology Exemplified by Neuroendocrine Neoplasms, Prostate Cancer, and Breast Cancer

“…While high correlation found between Ki and TBR indicated that the latter might be more accurate metrics than SUV for semi-quantitative assessment of [ 68 Ga]Ga-SST lesion uptake and treatment response monitoring [101]. Total functional tumor volume (TFTV) measured on [ 68 Ga]Ga-SST PET and computed by summing the volumes of all pathological foci was suggested as prognostic biomarker with cut-off of 13.8 cm 3 [102]. Somatostatin receptor expressing tumor volume (SRETV), defined as tumor volume with higher [ 68 Ga]Ga-SST uptake than 50% of SUV max within the volume of interest for each lesion, demonstrated prognostic value of survival [103].…”