A Case of Curative Surgery after Effective Chemotherapy for Gastric Adenocarcinoma with Enteroblastic Differentiation Accompanied by Synchronous Multiple Liver Metastases.

Introduction: Gastric adenocarcinoma with enteroblastic differentiation (GAED) is associated with a poor prognosis because of high rates of liver and lymph node metastases. While systemic chemotherapy is the standard treatment for gastric cancer (GC) with liver metastases, several studies suggest that hepatectomy, when combined with multimodal treatment, may provide a survival benefit. However, the role of surgical resection for GAED with liver metastases remains controversial.

Case presentation: A 71-year-old man presented with abdominal pain and nausea. Endoscopy revealed a type 2 tumor at the greater curvature of the gastric body. Contrast-enhanced computed tomography showed thickening and enhancement of the gastric wall, bulky lymph node metastases, and bilobar hepatic lesions, with the largest tumor measuring 60 mm in diameter. Histological examination of the stomach and liver tumors revealed adenocarcinoma composed of cuboidal or columnar cells resembling a primitive intestine-like structure with clear cells. Immunostaining showed heterogeneous cytoplasmic positivity for alpha-fetoprotein and spalt-like protein 4, leading to a diagnosis of GAED with liver metastases. Because the tumor was positive for human epidermal growth factor receptor 2 (HER2), chemotherapy with capecitabine, cisplatin, and trastuzumab was administered. After six cycles, the tumors had significantly decreased in size, and curative-intent surgery was performed, including distal gastrectomy, left lateral sectionectomy, and partial hepatectomy, successfully eradicating all five liver metastases. Histological examination of the liver metastases revealed extensive necrosis and fibrosis with no viable tumor cells. Adjuvant chemotherapy with the same regimen was continued for 1 year. At the time of this writing, the patient had remained recurrence-free for more than 2 years postoperatively.

Conclusions: We report a rare case of GAED with multiple liver metastases successfully treated with aggressive surgical resection following systemic chemotherapy. Trastuzumab-based chemotherapy may be a viable treatment option for HER2-overexpressing GAED. In addition, radical surgery for GAED with liver metastases might prolong the survival if the chemotherapeutic regimen was effective.