Cytokeratin19-2g2, a Novel Fragment of Cytokeratin19 in Serum, Indicating a More Invasive Behavior and Worse Prognosis in Breast Cancer Patients

Background Various studies have been searching for new tumor biomarkers for breast cancer for years. However, so far, few markers have been proved clinically useful except CA153. Based on knowledge that most adenocarcinomas including breast carcinoma expressed Cytokeratin19, the authors studied CK19-2G2,a novel fragment of cytokeratin19 shedding into serum in breast cancer patients. Patients and Methods The serum samples of four hundred and seventeen patients including three hundred and three (fifty-four DCIS and two hundred and forty-nine stage I-III) PBC patients and one hundred and fourteen MBC patients, eighty-one healthy controls and twenty-one breast benign disease patients were provided for measurement of CK19-2G2, CEA and CA153.The correlation between clinicopathological characters, prognosis and CK19-2G2 levels was further studied. Results The serum CK19-2G2 levels in breast cancer patients were significantly higher than that in healthy and benign controls. For breast cancer patients, CK19-2G2 levels in MBC were significantly higher than that in PBC patients. The sensitivities of CK19-2G2 for breast carcinoma are as high as CEA and CA153, and up to 71% in MBC patients. Serum CK19-2G2 levels (≥2 mU/mL) were associated with pathological stages, tumor size (≥2 cm), lymph node involvement, and HER2 status. Multivariate analysis revealed that high serum CK19-2G2 level was an independent factor for relapse ( P =  0.029) and death ( P =  0.040) in breast cancer patients. Conclusion Serum CK19-2G2 may be an independent indicator for prognosis and a candidate marker for monitoring metastasis in breast cancer.