A rare case of metachronous neuroendocrine tumor after a colorectal adenocarcinoma: qualitative critical review of synchronous and metachronous gastrointestinal NET

Abstract

Gastrointestinal neuroendocrine tumor (NET) associated with a metachronous intestinal adenocarcinoma is rare. We report the case of a 71-year-old man with an ileal NET. Patient has previously undergone a left colectomy for sigmoid cancer. We report a complete review both of the metachronous and synchronous NET. A comprehensive systematic literature search in PubMed, EMBASE, and MEDLINE identified a total of 35 relevant studies. This study includes an analysis of review articles, case reports, case series, retrospective studies and population-based studies. In the English literature to date, there are 21 case reports (19 synchronous cases and 2 metachronous cases), 3 case series and 3 review articles, and less than 10 retrospective studies or population-based studies. A total of 31 patients in 24 articles were included in the study: 28 patients with a synchronous gastrointestinal NET and colorectal adenocarcinoma and 3 patients with metachronous gastrointestinal NET and colorectal adenocarcinoma. The incidence of synchronous cancer (particularly for colorectal and gastric cancer) with a gastrointestinal NET ranges from 10 to 50%, while for the metachronous ones it is still unclear. This is the third metachronous case report and the first descriptive case of gastrointestinal NET diagnosed 2 years after a colorectal adenocarcinoma. An endoscopic follow-up program for gastrointestinal NET patients and/or for first-degree relatives of NET patients appears recommendable.

Metachronous ovarian carcinoma in patient with gastric neuroendocrine tumor diagnosed by 68Ga-DOTANOC and 18F-FDG positron emission tomography/computed tomography

“…Many hypotheses have tried to explain the association between NETs and SPMs: field-effect theory (i.e., common carcinogenic effect stimulates growth of neuroendocrine and SPM cancer cells), a genetic predisposition, exogenous mitogenic effects of secretory products from a primary tumor causing neoplastic transformation [secretory products include various neuropeptides such as gastrin, cholecystokinin (CCK), bombesin, and so on, which have specific growth factor properties, and non-neuropeptide growth factors such as platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and transforming growth factor (TGF)], or a combination of all these factors (4,14).…”

“…While there have been a few interesting case reports of NET-associated SPMs (8)(9)(10)(11)(12)(13)(14)(15)(16)(17), the majority of these studies have described the association between synchronous malignancies and NETs. Metachronous ovarian carcinoma, as a secondary cancer in patients with biopsy-proven, well differentiated gastric NET, is very rare.…”