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

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.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.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 (AUCCA15-3=0.702 vs. AUCCPN1=0.886, P<0.0001) and metastatic breast cancer (AUCCA15-3=0.629 vs. AUCCPN1=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 (AUCCA15-3+CPN1=0.916) and for distinguishing between metastatic and non-metastatic breast cancer (AUCCA15-3+CPN1=0.895).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.