Endocrine Abstracts

Background: Gastric neuroendocrine tumors (g-NETs) type I are increasingly recognized and are usually well-differentiated grade 1 neoplasms. However, rare cases of metastatic spread and adverse prognosis have been described in the literature.

Aims: The aim of this study was to evaluate the characteristics and the natural history of grade 2 g-NETs type I.

Materials and Methods: We collected retrospectively the data of patients with g-NETs type I and analyzed the epidemiological, histological and imaging features as well as the clinical outcome of grade 2 tumors.

Results: We analyzed the data of 60 patients (39 female) with mean age (±SD) at diagnosis 55±14 years and a median follow-up time 41 (range: 11-207) months. The median size of the neoplasms was 4.5 mm (range: 1-35 mm) while the median Ki-67 was 5% (range: 3-15%). In nine cases the GC1 were resected using endoscopic techniques while 11 patients were treated surgically (wedge resection or subtotal/total gastrectomy). Eight patients received treatment with long-acting somatostatin analogs (SSA). Two patients displayed regional lymph node infiltration while two others had liver metastases that were resected during primary tumor surgery. The Ki-67 of tumours with liver metastases was 8% and 15% whereas the tumor with the Ki-67:15% was Ga-DOTATATE PET/CT and FDG-PET/CT positive. No recurrence has been observed after surgical resection in patients with locally advanced or metastatic tumors after a median follow-up time of 95 (range: 54-158) months.

Conclusions: Despite the overall favorable prognosis of g-NETs type I, grade 2 neoplasms may in some cases display a more aggressive behavior being associated with distant metastases albeit with no apparent impact on patient’s prognosis.