[Clinical evaluation and tissue distribution of CA125 in patients with pleural effusion].

CA125 in serum and pleural effusion was measured in 51 patients with malignant effusion and 38 patients with benign effusion, and the tissue distribution of CA125 was investigated by immunohistochemical technique. The 51 malignant effusions were secondary to primary lung cancer. The 38 benign effusions were taken from 23 patients with tuberculous pleurisy, 9 patients with empyema, 5 patients with congestive heart failure and one patient with nephrosis. In the mean level and the positive rate of serum CA125, no significant difference was shown between primary lung cancer and tuberculosis or the other benign diseases. The mean level of CA125 in pleural effusion of primary lung cancer was significantly higher than that in pleural effusion of tuberculosis (p less than 0.01), and showed a tendency to increase compared to that in pleural effusion of the other benign diseases (p less than 0.1). The mean level of CA125 in pleural effusion of tuberculosis was significantly lower than that in the other benign diseases (p less than 0.02). The positive rate of CA125 in malignant effusion was 43.1% and the diagnostic specificity of it was 86.7%. CA125 was detected in carcinoma cells and activated mesothelial cells in pleural effusion and mesothelial cells of normal pleural tissue by immunohistochemical staining. These results suggest that the measurement of CA125 in pleural effusion is useful for differential diagnosis of the malignant effusion from the benign effusion and that CA125 in pleural effusion of pleuritis carcinomatosa is produced by not only carcinoma cells but also activated mesothelial cells.