Serum, pleural effusion, and ascites CA-125 levels in ovarian cancer and nonovarian benign and malignant diseases: a comparative study.

Objectives: Cancer antigen-125 (CA-125) is not a specific tumor marker and it is synthesized by normal and malignant cells of different origins. Recently it has been shown that various diseases are associated with increased CA-125 levels, especially in the presence of serosal fluid. The aim of this study is to investigate serum and fluid CA-125 levels in patients with different diseases.

Methods: A total of 133 patients and 23 healthy control cases were included in the study and divided into eight groups on the basis of disease and the presence of fluid in the serosal cavities. Serum and serosal fluid CA-125 levels were measured by a commercial enzyme immunoassay kit at the same time. Comparisons among the groups were made.

Results: Abnormal levels of serum CA-125 were observed in 76% of ovarian cancer patients; 96% in patients with ascites and 56% in patients without ascites. Moreover, elevated serum CA-125 levels were detected in 52% of patients with hepatic diseases, in 100% of patients with nongynecologic peritoneal carcinomatosis, and in 87% of patients with pleural effusion. Serum and fluid CA-125 levels were significantly higher in cases of ovarian cancer with ascites than in the other groups (P < 0.01). A positive correlation between serum CA-125 levels and ascites amounts was observed in cases of ovarian cancer with ascites (P < 0.01, r = 0.81). Furthermore, no correlation was observed between ovarian mass volume and serum CA-125 levels in ovarian cancer patients with stage I disease without ascites (P = 0.08, r = 0.48).

Conclusions: Although CA-125 levels may be considered a sensitive tumor marker in patients with epithelial ovarian cancer, it was determined that high serum CA-125 levels were closely related to the presence of serosal fluids and serosal involvement, whatever the origin is. These results should be considered in the interpretation of CA-125 elevation in patients with ovarian cancer.