Searching for primaries in patients with neuroendocrine tumors (NET) of unknown primary and clinically suspected NET: Evaluation of Ga-68 DOTATOC PET/CT and In-111 DTPA octreotide SPECT/CT

Abstract

BackgroundTo evaluate the clinical efficacy of In-111 DTPA octreotide SPECT/CT and Ga-68 DOTATOC PET/CT for detection of primary tumors in patients with either neuroendocrine tumor of unknown primary (NETUP) or clinically suspected primary NET (SNET).Patients and methods.A total of 123 patients were included from 2006 to 2009, 52 received Ga-68 DOTATOC PET/CT (NETUP, 33; SNET, 19) and 71 underwent In-111 DTPA octreotide SPECT/CT (50; 21). The standard of reference included histopathology or clinical verification based on follow-up examinations.ResultsIn the NETUP group Ga-68 DOTATOC detected primaries in 15 patients (45.5%) and In-111 DTPA octreotide in 4 patients (8%) (p < 0.001); in the SNET group, only 2 primaries could be detected, all by Ga-68 DOTATOC. In patients with NETUP, primary tumors could be found significantly more often than in patients with SNET (p = 0.01). Out of these 21 patients 14 patients were operated.ConclusionGa-68 DOTATOC PET/CT is preferable to In-111 DTPA octreotide SPECT/CT when searching for primary NETs in patients with NETUP but should be used with caution in patients with SNET.

Ga-68 DOTANOC PET/CT imaging in detection of primary site in patients with metastatic neuroendocrine tumours of unknown origin and its impact on clinical decision making: experience from a tertiary care centre in India

“…The results of our study are concordant with the studies done by Prasad et al (25) and Naswa et al (34). In our study, A C B rate of detection of primary sites was higher compared to study done by Screiter et al (26). Possible reasons could be differences in study-population characteristics and tumour-heterogeneity.…”

“…In a similar study by Naswa et al (34), the group identified primary site in 12 out of 20 patients (60%). In a recent study by Screiter et al (26) published in 2014, the study group found that Ga-68 DOTATOC PET/CT detected primary mitotic site in 45.5% (15 out of 33 patients) with most common site being the small intestine. In our study, we were able to identify the primary mitotic site in 40 out of 68 patients i.e., in approximately 59% patients.…”

“…In a recent study by Screiter et al (26) published in 2014, the study group found that Ga-68 DOTATOC PET/ CT detected primaries in 45.5% patients.…”

Localization of Unknown Primary Site with 68Ga-DOTATOC PET/CT in Patients with Metastatic Neuroendocrine Tumor

“…There may be also differences in detectability of tumor between 68 Ga-DOTANOC and 68 Ga-DOTATOC PET/CT, although the receptor affinity of both agents is similar for somatostatin receptor subtype 2, the predominant somatostatin receptor on NETs, whereas 68 Ga-DOTANOC has significantly higher affinity for somatostatin receptor subtype 3 and somatostatin receptor subtype 5 (18). In another study by Schreiter et al, patients with metastatic NET and unknown primary underwent either 68 Ga-DOTATOC PET/CT (n 5 33) or 111 In-octreotide SPECT/CT (n 5 50) (19). The detection rate of 46% for the unknown primary site with 68 Ga DOTATOC was similar to our findings and significantly better than 8% obtained with 111 In-octreotide.…”

Nowotwory neuroendokrynne jelita cienkiego i wyrostka robaczkowego — zasady postępowania (rekomendowane przez Polską Sieć Guzów Neuroendokrynnych)

“…Ga) are the preferred imaging method, particularly if the lesions are < 1 cm [66]. To locate the primary tumour site and assess the disease stage, SRI in correlation with multiphase CT/MRI is recommended.…”