Rationale: Mixed adenoneuroendocrine carcinoma (MANEC) is a rare neoplasm, and consensus on the treatment is unavailable.
Patient concern: A 60-year-old Chinese man presented with obstructive symptoms while eating and paroxysmal stomach pain for more than a month.
Diagnosis: MANEC was diagnosed based on clinical manifestations, imaging findings, and pathological examinations.
Interventions: The patient underwent radical gastrectomy and received XELOX adjuvant chemotherapy (oxaliplatin 200 mg day 1 + capecitabine 1.5 g twice a day) after surgery.
Outcomes: After 4 cycles of XELOX adjuvant chemotherapy were administered, abdominal computerized tomography and liver magnetic resonance showed liver metastasis.
Lessons: The therapy of gastric MANEC is based on surgical operation, and adjuvant chemotherapy program has an important influence on its prognosis. Therefore, further studying the effectiveness of XELOX adjuvant chemotherapy for gastric MANEC is necessary.