MON-LB057 A Descriptive Study of Type 1 Gastric Neuroendocrine Tumors and Its Association with Autoinmune Metaplasic Atrophic Gastritis in Hospital Clinico San Carlos

Abstract

INTRODUCTION Type 1 Gastric neuroendocrine tumors account for 70 to 80% of all gastric neuroendocrine tumors (G-NETs) and they are found more commonly in older adults, particularly women. They are associated with autoimmune metaplastic atrophic gastritis (AMAG) with or without pernicious anemia. Endoscopically, they are usually smaller than 1 cm and often multiple. These tumors present a non-aggressive evolution. Our aim is to describe different characteristics of type 1 G-NETs and to approach the presence of risk factors to develop G-NET in patients with AMAG. PATIENTS AND METHODS A descriptive and observational study of 16 patients diagnosed with AMAG (controls) and 31 patients diagnosed additionally with type 1 G-NET (cases). All of the 47 patients were retrieved from the Endocrinology Service of HCSC in the last 15 years. Variables between both groups were compared using the statistical program SPSS 23.0. RESULTS In the group of cases, 31.3% presented micronodular hyperplasia. 60.4% were grade 1 type 1 G-NET. 75.6% presented a single lesion. Median size was 0.4 cm (IQR 0.3-0.6). 41.9% of the lesions were located in the body of the stomach. Ki67 was ≤2% in 95.3% of the cases. Only 10.4% were treated with somatostatin analogs. Taking into account both groups: Mean age was 64.75 (SD 12.03) in controls and 63.47 (SD 11.35) in cases. 75% of controls and 62% of cases were female. The diagnosis of AMAG in controls was due to vitamin B12 deficiency in 68.8%. In cases, the diagnosis of G-NET was due to follow-up AMAG in 40.6%. We did not find differences between the personal and family history in both groups. 86.7% of controls and 71.8% of cases were non-smokers without reaching statistical significance. The presence of H. pylori was found in 18.8% of controls and in 3.1% of cases (p= 0.101). The median of vitamin B12 (normal range 180 -914 pg/ml) in controls was 186 (IQR 141.5-398.5) & 288 (IQR 204-386) in cases (p <0.05). There were no statistically significant differences in the levels of hemoglobin, ferritin or serum iron although the median values were lower in controls. Regarding autoimmunity, anti-parietal cell antibodies could protect the development of G-NET OR: 0.192 (0.038-0.956). We found a higher prevalence of intrinsic factor antibodies in controls (41.2% vs 21.7) that was not statistically significant (p=0.185). CONCLUSIONS In our sample, the presence of anti-parietal cell antibodies might be a protective factor against G-NET development. Vitamin B12 levels were significantly higher in cases than in controls. Further research confirming these data might help to establish the usefulness of Vitamin B12 levels in the early diagnosis of G-NET in patients with AMAG. Larger studies are necessary to assess whether the presence of intrinsic factor antibodies and H.Pylori infection are indeed associated with a lower risk of developing G-NETs in patients with AMAG. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.