This study was undertaken to determine whether human gastric adenocarcinoma expresses Fas-L, and whether serum sFas-L level changes in patients before and after gastrectomy, and whether Fas-L or sFas-L is related to tumor stage and histologic type. Retroactive analysis was performed in 38 cases of early gastric carcinoma (EGC) and 61 cases of advanced gastric carcinoma (AGC), including 38 cases of diffuse type and 61 cases of intestinal type, who underwent gastric resection from 1997 to 1998. Immunohistochemical staining for tumoral Fas-L detection and a sFas ligand ELISA kit for serum sFas-L detection were used. Fas-L was localized in neoplastic cells in 61% (23/38) of cases in the EGC group and 66% (40/61) of cases in the AGC group. The extent of Fas-L expression was variable, with both FasL-positive and -negative neoplastic regions occurring within a tumor. The mean serum sFas-L level was significantly higher in patients before treatment compared with that of controls, whereas the level in patients after gastrectomy was significantly lower as that of controls. Some patients whose preoperative serum sFas-L levels were within the normal limit expressed no tumoral Fas-L. Factors such as tumor stage, histologic subtype and other prognostic factors showed no correlation with Fas-L expression and serum sFas-L level. A statistically significant expression of tumoral Fas-L with concomitant increment of serum sFas-L in gastric adenocarcinoma was demonstrated. This finding suggested Fas-mediated apoptosis in response to Fas-L expression by gastric adenocarcinoma, providing evidence to support a Fas counterattack and indicated that the serum sFas-L level is a useful indicator in evaluating preoperative diagnosis and postoperative follow-up of gastric adenocarcinoma. The clinical stages of gastric adenocarcinoma of the intestinal and the diffuse type did not differ in their expression of Fas and sFas-L.

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