Poorly differentiated medullary carcinoma of the stomach

Background. The biologic behavior of poorly differentiated medullary carcinoma of the stomach is unclear. Methods. A clinicopathologic study on 74 poorly differentiated medullary carcinomas (PMC) and 73 non‐medullary carcinomas (NMC) of the stomach was done. PMC were defined as gastric carcinomas in which more than 50% of the tumor area contained poorly differentiated adenocarcinoma with no fibrous stroma. Results. They were characterized by a location in the upper 33% of the stomach (49%), grossly expansive growth (69%), frequent vascular permeation (57%), and simultaneous liver metastasis (15%). Although the 5‐year survival rate was similar for PMC and NMC, death of PMC was related more frequently to liver metastasis (47%) and less frequently to peritoneal dissemination (12%). The outcome of patients with PMC was influenced by frequent vascular permeation, extended lymph node metastasis, and simultaneous liver metastasis. Conclusions. These results indicate that PMC are characterized by expansive growth of the tumor and simultaneous or recurrent metastasis to the liver. Therefore, the biologic behavior of poorly differentiated medullary carcinoma is similar to that of well‐differentiated carcinoma of the stomach.