Clinicopathological features of hepatoid adenocarcinoma of the stomach: A multicenter retrospective study

Background Hepatoid adenocarcinoma of the stomach (HAS) is a rare and aggressive subtype of gastric cancer (GC), accounting for less than 1% of all cases. It is characterized by frequent liver metastasis recurrence and a poorer prognosis than conventional GC. However, established treatment guidelines for HAS are currently not available.In this report, we present the results of a clinicopathological study of 19 patients diagnosed with HAS, including seven patients with liver metastasis, conducted by the Hiroshima Surgical Study Group of Clinical Oncology (HiSCO) between 2016 and 2018. Aims The aim of the study was to retrospectively observe the outcomes of HAS with gastrectomy and hepatectomy for liver metastasis and determine relevant prognostic factor. We also examined the criteria and outcomes of hepatectomy for liver metastasis and aimed to suggest the optimal treatment for HAS, including chemotherapy. Methods and Results A total of 2147 patients underwent gastrectomy for GC at HiSCO‐affiliated institutions during the study period; 19 patients, all male with a mean age of 70.9 years, were diagnosed with HAS by hematoxylin‐eosin and immunohistochemical staining. Patients underwent gastrectomy at varying pathological stages: six at Stage I, three at Stage II, seven at Stage III, and three at Stage IV. Ten patients received postoperative chemotherapy and the 5‐year survival rate was 67.7% after gastrectomy. Among the seven patients with pre or postoperative liver metastasis, five patients underwent hepatectomy. Although one patient had recurrence, the 3‐year survival rate was 100% after hepatectomy. Conclusion Contrary to previous reports suggesting a 3‐year survival rate of approximmately 30% for HAS, our findings indicate that the prognosis for HAS may not be as poor as reported previously. This study contributes valuable insights into the management and potential treatment strategies for HAS.