The clinical significance of tumor-associated antigen RCAS1 expression in the normal, hyperplastic, and malignant uterine endometrium

Objective. A tumor-associated antigen, RCAS1, is recognized by 22-1-1 monoc lonal antibody. It was found in carcinomas derived from the uterus and ovar y and was especially strongly expressed in invasive cancers. A previous inv estigation showed the RCAS1 expression to be correlated with a poor prognos is in uterine cervical adenocarcinoma. In this study, we examined whether t he expression of RCAS1 is associated with the progression of the uterine en dometrial neoplasms. Methods. The expression of RCAS1 was evaluated by an immunohistochemical an alysis. The tissue specimens used in this study included 46 cases of normal uterine endometrium, 40 cases of hyperplasia, and 121 cases of adenocarcin oma. The relationship between RCAS1 expression and several clinicopathologi cal variables (clinical stage, histology, grade, myometrial invasion, lymph -vascular space invasion, and lymph node metastasis) was also assessed in e ndometrial adenocarcinoma. Results. RCAS1 was positive in 26% of the normal uterine endometrium specim ens (12 of 46 total cases), in 32% of the hyperplasia specimens (13 of 40 t otal cases), and in 68% of the adenocarcinoma specimens (83 of 121 total ca ses). As a result, the expression of RCAS1 was statistically higher in aden ocarcinoma than in the normal and hyperplastic endometrium (P < 0.0001). RC AS1 was statistically detected more frequently in grade 3 than in grade 1 o r 2 (P < 0.05); however, there was no correlation between the antigen expre ssion and the clinical stage, myometrial invasion, lymph-vascular space inv asion, or lymph node metastasis. Conclusion. RCAS1 expression might thus be associated with the malignant tr ansformation and poor differentiation observed in uterine endometrial adeno carcinoma. (C) 2000 Academic Press.