Discordance between serum level and tissue immunohistochemical staining of CA125 in endometrioid adenocarcinoma of the uterine corpus.

This study was designed to correlate tissue expression of CA125 with the corresponding serum value in endometrial cancer. The records of 52 endometrioid adenocarcinomas diagnosed were reviewed. Serum CA125 levels were examined before definitive surgery, and 20 U/ml was used as the cutoff value. Immunohistochemical staining for CA125 was assessed according to the ImmunoReactive Score. Statistical analyzes were performed to identify independent factor for high serum CA125 levels, including CA125 staining and the conventional pathologic features. Elevated serum CA125 levels were found in 15 of 52 patients (29%) (range, 0.1-172.1; mean 22.6 U/ml). The frequency of positive CA125 tissue staining (35/52, 67%) tended to be higher than that of elevated serum levels (p = 0.046). Fifteen patients with elevated serum CA125 levels statistically differed from the remaining 37 patients with normal serum CA125 level with respect to International Federation of Gynecology and Obstetrics (FIGO) stage (p = 0.027) and lymph node metastasis (p = 0.024), and tended to have positive washing cytology (p = 0.052). In multivariate analysis, elevated serum CA125 significantly correlated only with FIGO stage III, but not with tumor size or CA125 tissue staining. Intrauterine tumor may not be the main source of serum CA125 in endometrial cancer, and elevated serum level is closely related to the presence of disseminated cancer cells in the peritoneal cavity.