Alpha 1-antitrypsin, alpha 1-antichymotrypsin, and alpha 2-macroglobulin in human gastric carcinomas: a retrospective immunohistochemical study.

One hundred twenty-six gastric carcinomas (68 advanced cancers and 58 early cancers) were examined immunohistochemically for alpha 1-antitrypsin (AAT), alpha 1-antichymotrypsin (ACT), and alpha 2-macroglobulin (AMG) within tumor cells. The incidence of these three protease inhibitors was markedly higher in advanced than in early cancers, regardless of the histologic type of gastric carcinoma. In advanced cancers the incidence of both AAT and AMG was significantly higher in well-differentiated adenocarcinomas than in poorly differentiated adenocarcinomas, but no difference was observed in the expression of ACT between these two types of advanced carcinomas. Eighty per cent of the AAT-positive advanced carcinomas had ACT, and 40 per cent of these tumors also contained AMG. The two-year survival rates clearly indicated that well-differentiated adenocarcinomas with AAT have worse prognoses than well-differentiated adenocarcinomas without AAT, but there was no relation between the expression of ACT or AMG and prognosis. These results strongly suggest that the presence of protease inhibitors in gastric carcinomas is related to the invasive growth of the tumors and that AAT is a tissue tumor marker of well-differentiated adenocarcinomas of the stomach. It may also serve as a biologic marker of high malignancy in patients with these gastric cancers.