Aim: To investigate the prognostic significance of cancer antigen 15-3 (CA15-3) in primary breast cancer (BC).
Patients and methods: This prospective study included 368 women: 62 patients with benign breast disease (BBD), 159 patients with invasive BC and 88 healthy blood donors (control). The median follow-up was 76 months (range, 43-99 months). Serum CA15-3 was measured with LIAISON® CA15-3® chemilluminescence immunoassay.
Results: Significantly high levels of CA15-3 were found in patients with BC compared to controls (p=0.029), but not to the BBD group (p=0.16). Preoperative CA15-3 in patients with BC was significantly associated with tumor size (p=0.003), TNM stage (p=0.005), vascular invasion (p=0.018) and tumor necrosis (p<0.05). Increased CA15-3 (>30 U/ml) concentrations were more often found in patients with larger tumors (p<0.05), advanced stage (p=0.004) and node-positive disease (p=0.007). Patients with normal levels of CA15-3 had better recurrence-free survival (RFS) than those with elevated levels (p<0.001). After adjustment for T-stage, grade, tumor necrosis, estrogen receptor (ER) and progesterone receptor (PR) status, CA15-3 remained an important preoperative characteristic with independent impact on RFS (hazard ratio=4.4, 95% confidence interval=1.5-13.1, p=0.007). The independent prognostic contribution of CA15-3, considered on a continuous scale was significant among subgroups of the BC patients with ER/PR-positive (p=0.002), node-positive (p=0.028), node-negative (p=0.003), T1-stage node-negative (p=0.017), luminal-A (p=0.003), luminal-B (p=0.028) and human epidermal growth factor receptor-2 (HER2)/non-luminal disease (p=0.045).
Conclusion: Preoperative measurement of CA15-3 allowed identifying high-risk of recurrence for patients with primary BC and might be combined with existing prognostic factors in planning adjuvant treatment.