Whole Body Dynamic 68Ga-DOTATOC PET/CT in Neuroendocrine Tumors

Study Overview
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Brief Summary
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Neuroendocrine tumors (NET) are a network of rare tumors with common embryological origin. Functional imaging plays a major role in the extension assessment and tumor characterization of NETs. SPECT/CT with 111In-pentetreotide is the recommended test when tumors are well differentiated (grade G1 or G2). It has a real interest in diagnosis, in therapeutic decision-making (in particular by cold somatostatin analogues or in PRRT) and in the systematic follow-up of patients. Nevertheless, SPECT/CT procedure makes for a relatively long review. In addition, scintigraphy has a lower spatial resolution than PET technology and remains of limited interest for signal quantification. However, the ability to locate and quantitatively measure the absorption of radiopharmaceuticals in the target tissues is a major challenge in oncology for the characterization of the disease. Recent developments in radiopharmacy have made it possible to target NETs in PET imaging through the use of somatostatin analogues coupled with positron emitters, called 68Ga-DOTA peptides. The diagnostic performance of 68Ga-DOTApeptide PET/CT appears to be superior to SPECT/CT with 111In-pentetreotide. A marketing authorization has thus recently been issued in France for the use of 68Ga-DOTATOC. Historically, the recommended quantification method in PET was based on the instantaneous measurement in static acquisition (3D) of the maximum of the standardized uptake value (SUVmax). This approach has the disadvantage to measure the signal at a time t for a single voxel of the image. Dynamic acquisition methods (4D) have been proposed to extract a radiotracer absorption coefficient (Ki) for a lesion. Several studies have demonstrated the superiority of Ki versus SUVmax in 18FDG PET/CT for the diagnostic management, therapeutic evaluation and prognosis of various solid cancers. However, no work has validated this approach in PET / CT at 68Ga-DOTATOC as part of the prognostic evaluation of NETs. The objective of the study is to evaluate the prognostic value of the tumor absorption coefficient Ki resulting from a 4D whole-body dynamic acquisition in PET / CT at 68Ga-DOTATOC in patients with well-differentiated NETs grade I or II according to the WHO classification

Official Title
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Prognostic Interest of a Whole Body Dynamic PET Acquisition in Pre-therapeutic 68Ga-DOTATOC PET/CT for Neuroendocrine Tumors

Conditions
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Neuroendocrine Tumors

Intervention / Treatment
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* Device: Whole Body Dynamic 68Ga-DOTATOC PET/CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient majeur ≥ 18 year old Présenting a well differentiated neuroendocrine tumor (G1 ou G2) Indication performing a68Ga-DOTATOC PET/CT non-opposition Exclusion Criteria: Patient <18 years old Breastfeeding/ pregnancy Other type of tumor Refusal of participation

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Device: Whole Body Dynamic 68Ga-DOTATOC PET/CT|68Ga-DOTATOC PET-CT will be performed in the nuclear medicine department of the University Hospital of Brest on a Biograph mCT S64 machine (Siemens medical, Erlangen, Germany) Time of Flight system after intravenous injection of 150MBq of 68Ga-DOTATOC. In the usual conditions for performing this exam, the patient must remain at a strict rest for 60 minutes following the injection of the tracer and before a static 3D acquisition. For this protocol, a complementary 4D dynamic acquisition (15-60 minutes post-injection) will be performed during this usual rest period.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Progression free survival (PFS) | To evaluate the prognostic value of lesionnal Ki on progression-free survival at 2 years and compare it with SUVmax (static 3D acquisition) in patients with metastatic well-differentiated NET | 2 years | 
| Recidive free survival (RFS) | To evaluate the prognostic value of Ki lesion on progression-free survival at 2 years and compare it with SUVmax (static 3D acquisition) in patients with localised well-differentiated NET | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation between lesionnal Ki and immunochemistry markers | Evaluate the statistical correlation between lesional Ki versus SUVmax with NET immunohistochemistry markers expression (SSTR2, SSTR3, and SSTR5; BCL2, Phospho-MTOR expression PD-L1 by tumor cells and immune cells, intra-tumor CD8 + lymphocytes, tumor necrosis surface) | 0 to 2 years | 
| Predictive value of non-event survival (PFS+RFS) | To evaluate the predictive value of non-event survival (PFS+RFS) with a ΔKi approach in patients receiving an intermediate therapeutic assessment examination (somatostatin analogues or PRRT with 177Lu-DOTATATE), and compare it with a ΔSUVmax approach | 6 months to 2 years | 
| Correlation between 68Ga-DOTATOC PET/CT and/or 111In-pentetréotide SPECT/CT and 177Lu-DOTATATE SPECT/CT | Evaluate the statistical correlation between the SUVmax assessed with 68Ga-DOTATOC PET/CT and/or 111In-pentetréotide SPECT/CT and 177Lu-DOTATATE SPECT/CT | 0 to 2 years | 
| Prognostic value of Ki versus usual prognostic parameters | To evaluate the prognostic value on non-event survival (PFS+RFS) at 2 years of Ki and clinical parameters (sex, age), biological (CgA assay), pathology (grade, differentiation, Ki67 expression, BCL2, phospho-MTOR). | 2 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Positron Emission Tomography Computed Tomography, whole body dynamic acquisition, Gallium 68