The biological tumor markers' myopia: a model with CA 125 and second-look in ovarian cancer.

Preoperative CA 125 levels were measured in 36 patients with advanced epithelial ovarian carcinoma in clinical response undergoing a second-look operation. All the patients had positive levels (greater than 35 U/ml) of this tumor marker at diagnosis. The correlation between antigen levels and disease status at surgery revealed a sensitivity of this assay of 0.55 (only 11/20 patients still with tumor had positive levels) and a specificity of 0.94 (15/16 patients with no tumor had less than 35 U/ml). The predictive value of a positive test was 0.92. This method unfortunately proved unable to recognize microscopic residual tumor burden, less than 0.5 cm.