Serum Carboxypeptidase N1 Serves as a Potential Biomarker Complementing CA15-3 for Breast Cancer

Background: The incidence and mortality of breast cancer are increasing annually. Breast cancer seriously threatens women's health and quality of life. We aimed to measure the clinical value of CPN1, a new serum marker of breast cancer and to evaluate the efficacy of CPN1 in combination with CA15-3. Methods: Seventy samples of breast cancer with lymph node metastasis, seventy-three samples of nonmetastatic breast cancer and twenty-five samples of healthy human serum were collected. Serum CA15-3 concentration was determined by Roche Elecsys, and serum CPN1 concentration was determined by ELISA. Results: In breast cancer patients, serum CPN1 concentration was positively correlated with tumour size, clinical stage and CA15-3 concentration (r = 0.376, P<0.0001). ROC curve analysis showed that the optimal critical concentration of CPN1 for breast cancer diagnosis was 32.8pg/ml. The optimal critical concentration of CPN1 in the diagnosis of metastatic breast cancer was 66.121pg/ml. CPN1 has a greater diagnostic ability for breast cancer (AUC CA15-3 =0.702 vs. AUC CPN1 =0.886, P<0.0001) and metastatic breast cancer (AUC CA15-3 =0.629 vs. AUC CPN1 =0.887, P<0.0001) than CA15-3, and the combined detection of CA15-3 and CPN1 can improve the diagnostic efficiency for breast cancer (AUC CA15-3+CPN1 =0.916) and for distinguishing between metastatic and non-metastatic breast cancer (AUC CA15-3+CPN1 =0.895). Conclusion: CPN1 can be used as a new tumour marker to diagnose and evaluate the invasion and metastasis of breast cancer. The combined detection of CPN1 and CA15-3 is more accurate and has a certain value in clinical application.