PET and PET/CT with⁶⁸Gallium-Labeled Somatostatin Analogues in Non GEP-NETs Tumors

Abstract

Somatostatin (SST) is a 28-amino-acid cyclic neuropeptide mainly secreted by neurons and endocrine cells. A major interest for SST receptors (SSTR) as target for in vivo diagnostic and therapeutic purposes was born since a series of stable synthetic SST-analouges PET became available, being the native somatostatin non feasible for clinical use due to the very low metabolic stability. The rationale for the employment of SST-analogues to image cancer is both based on the expression of SSTR by tumor and on the high affinity of these compounds for SSTR. The primary indication of SST-analogues imaging is for neuroendocrine tumors (NETs), which usually express a high density of SSTR, so they can be effectively targeted and visualized with radiolabeled SST-analogues in vivo. Particularly, SST-analogues imaging has been widely employed in gastroenteropancreatic (GEP) NETs. Nevertheless, a variety of tumors other than NETs expresses SSTR thus SST-analogues imaging can also be used in these tumors, particularly if treatment with radiolabeled therapeutic SST-analouges PET is being considered. The aim of this paper is to provide a concise overview of the role of positron emission tomography/computed tomography (PET/CT) with 68Ga-radiolabeled SST-analouges PET in tumors other than GEP-NETs.

99mTc-EDDA/HYNIC-TOC in management of patients with head and neck somatostatin receptor positive tumors

“…Although Hurthle cell carcinomas do not belong to the traditional group of NETs, positive SSR in these tumors could provide, especially in negative radioiodine cases, new treatment option like PRRT [4,19,20].…”

“…Rarely, NETs from other sites can also metastasize to the head and neck region [3]. Some other types of head and neck tumors; medullary thyroid carcinoma (MTC), meningioma, Hurthle cell carcinoma, also showed somatostatin receptors (SSRs) on the cell membrane surface [4]. SRS is indicated in the staging of SSR overexpressing tumors, restaging, detection of eligibility for "cold" somatostatin analogues (SSAs) or somatostatin receptors directed radionuclide therapy (peptide radionuclide receptor therapy -PRRT).…”

68Gallium DOTANOC-PET Imaging in Lung Carcinoids: Impact on Patients' Management

“…Previously published series which focused exclusively/ mainly on patients diagnosed with LC were small [20,27], the largest including only 26 patients [32] (Table 5). To our knowledge, our series is one of the largest series exploring "real" role of 68 Ga-DOTANOC PET exclusively in patients diagnosed with LC.…”

“…proved diagnosis, staging, and treatment of patients diagnosed with LC [20,21] [26,27]. 68 Ga-DOTA imaging has shown superiority to somatostatin receptor scintigraphy (such as Octreoscan), iodine-131-meta-iodobenzylguanidine scintigraphy, and MRI [28].…”

“…It is unclear whether any of these tracers are superior to others for LC, since such patients have been underrepresented in previously published large series on patients with NETs exploring 68 Ga-DOTA-PET imaging (accounting for 10-12% of the patients reported [29,31]) due to their low incidence [20]. Previously published series which focused exclusively/mainly on patients diagnosed with LC were small [20,27], the largest including only 26 patients [32]. As per European Neuroendocrine Tumour Society (ENETS) [12], North American Neuroendocrine Tumor Society (NANETS) [33], and National Comprehensive Cancer Network (NCCN) [34] guidelines, the use of 68 Ga-DOTA-PET scans is preferable to standard somatostatin receptor scintigraphy whenever available, having a potential role for selection of patients for treatment with PRRT, identification of primary tumour, and presurgical staging.…”