Endoscopic Treatment of Early Mixed Adenoneuroendocrine Carcinoma of the Stomach (MANEC): Is Everything Clear?

The article presents a rare clinical case of non-invasive mixed adenoneuroendocrine carcinoma (MANEC) of the stomach. Objective: To demonstrate the experience of endoscopic diagnosis and treatment of mixed adenoneuroendocrine carcinoma of the stomach through a clinical case report. Case report. At expert upper GI endoscopy performed at the P.A. Herzen Moscow Oncology Research Institute, a laterally-spreading epithelial lesion with signs of malignancy was identified in the gastric body, characterized by dilated, pathologically tortuous capillaries and areas with loss of the pit pattern. The patient underwent endoscopic submucosal dissection (ESD). According to the histopathological examination, the tumor demonstrated a mixed structure containing both foci of moderately differentiated adenocarcinoma and areas of well-differentiated grade 1 neuroendocrine tumor. The endoscopic treatment was considered radical (R0 resection). Follow-up procedure 6 months after the radical procedure was performed - distant liver metastases were detected, indicating rapid disease progression and ultimately leading to the patient’s death. Conclusion: Intraluminal endoscopic treatment does not provide adequate oncological outcomes in patients with non-invasive mixed adenoneuroendocrine tumor of the stomach and should not be considered a preferred or radical treatment modality.