CA 125 is an indicator for pleural metastases in breast cancer

In this study we analyzed the role of CA 125 serum levels in the diagnosis and follow-up of pleural metastases in breast cancer patients. CA 125 serum levels were measured in patients with lung and/or pleural metastases: a) at the time of the detection of the metastases, b) 3 months thereafter during therapy and c) before and after drainage of pleural effusions. In all patients the occurrence of metastases at other localisations was excluded. For CA 125 measurement ELISA sandwich assays were performed. In 76 patients with metastases CA 125 levels were elevated in 8% of patients with lung metastases, in 89% with pleural metastases and in 94% with both sites of metastases. In patients with lung metastases, the CA 125 concentrations did not follow the clinical course of the disease, while in patients with pleural metastases CA 125 levels followed the course of disease in 25 of 25 progressions and in 5 of 6 remissions. After the puncture of pleural effusions the CA 125 levels decreased in 7 of 14 patients and remained stable in the other 7 patients. CA 125, an established marker for diagnosis and follow-up of ovarian cancer, could also be considered as a relatively selective marker for the diagnosis and follow-up of pleural metastases in breast cancer patients.