Comparison of the diagnostic accuracy of CA27.29 and CA15.3 in primary breast cancer

Background: A new, fully automated method that measures the breast cancer-a ssociated glycoprotein CA27.29 has become commercially available. The aim o f the present study was to compare this CA27.29 assay with the assay that m easures CA15.3 in primary breast cancer. Methods: The study was performed retrospectively on preoperative serum samp les collected from 275 patients with untreated primary breast cancer (154 n ode positive and 121 node negative). Eighty-three healthy control subjects were also evaluated. CA27.29 was measured using the fully automated Chiron Diagnostics immunochemiluminescent system (ACS:180 BR). CA15.3 was measured with a manual immunoradiometric method (Centocor CA15.3 RIA). Results: In healthy subjects, CA15.3 was significantly higher than CA27.29 (P <0.0001). On the other hand, in breast cancer patients CA27.29 was highe r than CA15.3 (P = 0.013). The mean value found in the control group plus 2 SD was chosen as the positive/negative cutoff point. The overall positivit y rates were 34.9% for CA27.29 and 22.5% for CA15.3. The area under the ROC curve was greater (P <0.001) for CA27.29 (0.72) than for CA15.3 (0.61). Bo th markers showed a statistically significant, direct relationship, with pa thological stage being higher in node-positive than in node-negative cases and in larger than in smaller tumors. Neither CA27.29 nor CA15.3 showed sig nificant associations with age, menopausal status, or tumor receptor status . Conclusions: CA27.29 discriminates primary breast cancer from healthy subje cts better than CA15.3, especially in patients with limited disease. Prospe ctive studies are necessary to confirm this conclusion. (C) 1999 American A ssociation for Clinical Chemistry.