Serum CEA levels in patients with gastric carcinoma correlate with the tumorigenicity of their xenografts in nude mice.

We examined the correlation among preoperative serum carcinoembryonic antigen (CEA) levels, staining properties of the tumors by CEA immunohistochemistry and the tumorigenicity of their xenografts in nude mice, in 28 patients with gastric cancer. Eleven (40 per cent) of them were positive for serum CEA (greater than or equal to 2.5 ng/ml) and seven (25 per cent) of the xenografts were tumorigenic in nude mice. All the tumorigenic cases were positive for serum CEA (p less than 0.001) and the mean value of the serum CEA level in the patients with tumorigenic neoplasms was 20.8 ng/ml, being significantly higher than that (1.4 ng/ml) in the patients with non-tumorigenic neoplasms (p less than 0.001). Twenty-five of the 28 carcinomas (89 per cent) were positive for CEA staining in their cancer cells by the ABC method and CEA localization correlated with tumorigenicity (p less than 0.05). These results suggest that the serum CEA level in patients is correlated with the tumorigenicity of their gastric carcinoma xenografts in nude mice and may account for the poor prognosis of patients with high serum CEA.