Pathology and prognosis of gastric carcinoma: well versus poorly differentiated type.

BACKGROUND: The most important parameters predicting outcome of patients with gastric carcinoma are the depth of wall invasion and the status of lymph node metastasis, but the prognostic significance of histologic type is unclear. The aim of this study was to clarify the prognostic value of two major histologic types of gastric carcinoma, that is well and poorly differentiated types.

METHODS: Histopathologic findings and outcomes of 504 patients with gastric carcinoma were evaluated by well and poorly differentiated types. Well differentiated gastric carcinoma (WGC) included papillary and tubular adenocarcinomas, poorly differentiated medullary carcinoma, and well differentiated mucinous carcinoma; whereas poorly differentiated gastric carcinoma (PGC) included poorly differentiated scirrhous carcinoma, signet ring cell carcinoma, and poorly differentiated mucinous carcinoma.

RESULTS: Patients with WGC were characterized by old age, male predominance, tumor location in the lower third of the stomach, small tumor size, and liver metastasis; whereas patients with PGC were distinguished by their tumor location in the middle third of the stomach, serosal invasion, lymph node metastasis, advanced stage, and peritoneal dissemination. The overall 5-year survival rate for patients with WGC was higher than that for patients with PGC (76% vs. 67%; P = 0.058), especially for patients with >/= 10 cm tumors (42% vs. 14%; P = 0.017). The 5-year survival rate for patients with serosa positive but node negative tumors was higher in WGC patients than in PGC patients (83% vs. 59%; P = 0.086); whereas the 5-year survival rate for patients with serosa negative but node positive tumors was lower in WGC patients than in PGC patients (63% vs. 88%; P = 0.008). Multivariate analysis indicated that among pathologic variables of the tumor, histologic type (WGC vs. PGC) was one of the independent prognostic factors.

CONCLUSIONS: Histologic type is important for estimating the tumor progression and outcomes of patients with gastric carcinoma. In addition to the depth of wall invasion and status of lymph node metastasis, histologic type, including well or poorly differentiated type, should be evaluated in the management of gastric cancer.