Clinical Usefulness of Cancer Antigen 15-3 in Breast Cancer Patients Before and After Surgery

Background: Cancer Antigen 15-3 (CA 15-3) is a tumor-associated antigen used as serum marker for breast cancer surveillance in patients and for monitoring the response to treatment. Aim of this study was to retrospectively evaluate CA 15-3 as a prognostic factor in early detection of breast cancer relapse as well as to analyze the statistical correlation between CA 15-3 levels and clinical-pathological parameters including staging, grading, estrogen and progesterone receptors. Methods: Sera of 726 women with breast carcinoma obtained preoperatively and postoperatively were assayed for CA 15- 3 by chemoluminescent immunometric assay. Results: We found that the mean serum CA 15-3 levels in patients before surgery were significantly higher (36.59 U/ml) compared with those of CA 15-3 after surgery (27.11 U/ml). We also found that elevated preoperative serum levels of CA 15-3 were significantly correlated with the presence of metastatic disease. In particular, among 305/700 patients (43,6%) that displayed over cut-off (>40U/ml) preoperative levels of CA 15-3, 94 patients (30,8%) developed advanced disease (metastases to distant sites). By contrast, in a subgroup of 395/700 patients (56.4%) with CA 15.3 serum levels < 40U/ml, only 32/305 patients (8%) showed signs of advanced disease during follow-up. Cox regression analysis revealed that only the presence of metastasis and the increased serum levels of CA 15-3 after surgery are significant risk factors for relapse of disease. Conclusion: Elevated preoperative concentrations of CA 15-3 may be a useful predictive factor for cancer progression in postoperative patients.