[Value of the determination of CA 15-3 in the diagnosis of malignant pleural effusion].

In 160 consecutive patients with pleural shedding, antigen CA 15-3 values in pleural fluid were determined, in a prospective way using monoclonal antibodies (115D8 and DF3). In 49 patients with malignant pleural shedding, the mean value of CA 15-3 (47.6 U/ml) was significantly higher (p less than 0.01) to the values in the 111 benign ones (12.9 U/ml). Its sensibility for malignity, with a trough level of 27 U/ml, was of 37% with an specificity of 96%. When a specificity of 100% was required its sensibility (18%) was significantly lower to the carcinoembryonic antigen (CEA) (33%), measured simultaneously with comparative purposes. The simultaneous determination of both markers raised sensibility to 39%, without reaching statistical signification. In the ten patients whose pleural sheddings was secondary to breast carcinoma, both minimum (15 U/ml) as medium (110 U/ml) values, as well as CA 15-3 sensibility (80%), were higher to the ones found in the rest of patients with shedding of malignant origin, but without a clear superiority over the values obtained with CEA. Based on these results, we conclude that the usefulness of the determination, as a tumoral marker, in pleural fluid, of CA 15-3 is lower than CEA and that its simultaneous determination seems not justified. We think that its specific usefulness in pleural sheddings secondaries to breast carcinomas deserves a study with a bigger sample.