Primary study of lymph node metastasis-related serum biomarkers in breast cancer.

The aim of this study was to detect the pretreatment serum protein profiles of breast cancer patients by mass spectrometry (MS) to screen candidate tumor biomarkers, which will supply a simple, accurate, and minimally invasive method to predict the axillary lymph node metastasis of breast cancer. We used magnetic bead-based weak cation-exchange chromatography followed by matrix-assisted laser desorption and ionization time-of-flight MS to detect proteins in the sera of 54 cases of axillary node-negative breast cancer, 47 cases of axillary node-positive breast cancer, and 101 healthy controls. The protein profiles were analyzed to screen tumor biomarkers and lymph node metastasis-associated proteins to establish and verify a diagnostic model. Comparison of the protein profiles between the two cancer groups resulted in a total of 111 discriminate m/z peaks that were associated with breast cancer. Furthermore, 40 discriminate m/z peaks were detected between breast cancer patients with and without axillary node metastases. Four protein m/z peaks at 5,643, 4,651, 2,377, and 2,240 were used to construct a diagnosis model, and cross-validation indicated that breast cancer with and without axillary node metastasis was identified with 87.04% sensitivity (47/54), 87.23% specificity (41/47), and 87.13% accuracy (88/101). These proteins could potentially be used as predictive biomarkers to distinguish between breast cancer patients with or without lymph node metastasis.