Highly aggressive behavior and poor prognosis of small cell carcinoma in the stomach: flow cytometric and immunohistochemical analysis.

Small cell carcinoma of the stomach has an aggressive feature, and the survival rate of the patients is poor. The purpose of this study was to determine the clinical course, and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the stomach. Medical records of 8 patients who presented with small cell carcinoma of the stomach were retrospectively reviewed. Primary tumors were studied by flow cytometric analysis and immunohistochemical staining for the p53 protein, PCNA (proliferating cell nuclear antigen), factor VIII related antigen (specific for endothelial cells), VEGF (vascular endothelial growth factor) and PD-ECGF (platelet-derived endothelial cell growth factor). DNA aneuploid was observed in 4 cases. Staining for the p53 product was positive in 50% of all the cases. The average PCNA labeling rate (LR) was 71.3+/-9.9%. Positive VEGF expression was found in 7 tumors and positive PD-ECGF expression was found in all tumors. The estimated median survival was 252 days for all the patients. Liver metastases were observed in 4 of the 8 patients, however, surgery and chemotherapy have given us one long-term survivor (43 months). Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Moreover, both VEGF and PD-ECGF positivity are well-characterized inducers of hepatic metastasis.