Tumor markers in the diagnosis of malignant serous effusions.

To assess the possibility of increasing the detection rates of cytological examination in malignant effusions by the selection of specific tumor markers for a given type of tumor, we measured CEA, CA 19.9, CA 15.3, MCA, PSA, and AFP in malignant effusions from 89 patients with the following primary malignancies: colon, stomach, breast, liver, prostate, lung, and kidney. Cytological examination was positive in only 35 of 89 patients (40\%), while the tumor markers were positive in 72 of 89 cases (80\%). However, apart from small cell lung and kidney cancers, where the lack of a specific tumor marker resulted in no advantage, in the other types of tumors, the specific marker for each tumor identified correctly malignant effusions in 72 of 74 cases (97\%). In fact, CEA was positive in 11 of 11 effusions induced by colorectal cancer; CA 19.9 in 28 of 30 gastric cancer effusions, while MCA and CA 15.3 were positive in breast cancer effusions (16/22 and 20/22). Finally, elevated AFP and PSA indicated hepatocellular and prostate cancer, respectively. In conclusion, in cancer patients with elevated effusion levels of specific tumor markers, the effusions could be considered of a malignant nature even without cytologically demonstrable tumor cells.