beta-microseminoprotein in gastric carcinoids: A marker of tumour progression

Gastric carcinoid disease may have a highly varying clinical course dependi ng on the malignancy of the tumour. Many biochemical markers, such as pepti des and biogenic amines, have been found in carcinoid tumour tissue but non e has been reported to be useful as a predictor of the degree of mal ig nan cy of the carcinoid. beta-Microseminoprotein is a small disulphide-rich pro tein with unknown function present in the secretions on most mucosal surfac es in the body, including the stomach where it is also found in some endocr ine cells. We have studied beta-microseminoprotein by immunohistochemistry in the tumour tissue of 29 patients with gastric carcinoid disease. beta-Mi croseminoprotein was present in the tumour tissue in 62% of the patients an d its presence was correlated to tumour diameter and tissue invasion depth. The presence of beta-microseminoprotein in tumour tissue was corroborated by in situ hybridisation. All 4 patients with the solitary sporadic type of tumour and at 6 patients with metastasis had positive immunostaining of th e tumour tissue. The serum concentration of beta-microseminoprotein, measur ed by radioimmunoassay, was increased in all but 2 of 13 patients with gast ric carcinoid disease. To a large part the increase was due to the concomit ant atrophic corpus gastritis. We conclude that beta-microseminoprotein in tumour tissue is a marker of tumour progression and that measurement of bet a-microseminoprotein in serum is less informative than immunohistochemistry .