A gastric neuroendocrine carcinoma with good prognosis after chemotherapy combined with immunotherapy: A case report (CARE-compliant)

Abstract

Introduction: Gastric neuroendocrine carcinoma (GNENs), as a highly malignant gastrointestinal tumor, is characterized by easy postoperative metastasis, and its prognosis has always been poor compared to other gastrointestinal tumors. Due to its rarity, there have been few case reports and studies on it. As of now, there is no clear diagnosis and treatment sequence and guidelines. In this report, we present a case of GNENs that underwent first-line treatment after surgery. The patient achieved an excellent prognosis and survival after a combination of chemotherapy resistance and immunotherapy. This report aims to provide valuable reference and guidance for the treatment of GNENs in the future. Therefore, we conducted a literature review on GNENs. Patient concerns: A 61-year-old man was admitted to the hospital with complaints of upper abdominal distension and discomfort that had been persistent for 1 month. During the endoscopy examination, a 2.5 cm irregular deep mucosal defect was observed at the center of the gastric angle. The defect appeared covered with dirty moss, had a hard texture, and exhibited a tendency to bleed upon contact. Diagnosis: Biopsy results confirmed the presence of a medium to poorly differentiated adenocarcinoma in the gastric horn. Subsequently, the patient underwent surgery, and the removed specimen was diagnosed as GNENs. Intervention: Postoperative chemotherapy combined with immunotherapy Outcome: The patient in this case achieved a good prognosis and extremely long survival [overall survival > 3 years+] after receiving first-line treatment, which included chemotherapy, drug resistance and immunotherapy, and is currently in good health condition. The tumor is not sensitive to the standard EP regimen for neuroendocrine carcinoma, but after being replaced with oxaliplatin based regimen combined with immunotherapy, partial response was obtained, indicating a synergistic effect between chemotherapy and immunity. After treatment, it remained stable for a considerable period of time. Conclusion: Immunotherapy, as a new mode of cancer treatment can provide new guidance and ideas for the treatment of GNENs.