Gastric metaplasia and duodenal neuroendocrine neoplasms: True causality or simple coincidence?

Introduction:Duodenal neuroendocrine neoplasms (dNENs) are heterogeneous tumors, whose natural history is poorly known. Duodenal gastric metaplasia (DGM) is considered to be a precancerous lesion which is generally related to chronic inflammation as first sign. No data are available regarding its possible role as a risk factor for dNEN occurrence. Aim(s):To assess the prevalence of DGM in a cohort of histologically confirmed dNEN. Materials and methods:Subgroup analysis of a retrospective study including all consecutive patients with dNEN, who underwent surgical resection between 2000-2019 and observed at eight Italian tertiary referral centers. Results:109 patients with histologically confirmed dNEN were included in the study. Signs of DGM associated with the presence of dNEN were reported in 14 patients (12.8%). Among these patients, 9 had a bulbar dNEN, in 4 the dNEN was located in the 2nd portion of the duodenum; 10 were G1, 3 G2 and in one patient the ki67 was not available; one patient only was diagnosed with Multiple Endocrine Neoplasia type 1 (MEN1) syndrome. Four patients had a gastrinoma, one a somatostatinoma. Four patients were treated with proton pump inhibitor. At the end of the study, 3 patients had died because of disease progression. Conclusion:Our findings might suggest that DGM could represent a risk factor for the occurrence of dNEN, however, the actual relationship as well as the clinical relevance of this possible association require to be further clarified. Based on these preliminary findings, one might speculate that the presence of DGM could precede the development of dNEN, which should be kept in mind in the endoscopic follow-up of patients with DGM