Serum Cytokeratin 18 as a Potential Early Marker for Chemotherapy Response in Breast Cancer Patients: A Prospective Study

Background: Currently, it is well recognized that response to neoadjuvant chemotherapy is an important predictive factor for survival in breast cancer patients. However, it is still an area of research about which patient would respond to the neoadjuvant chemotherapy. Methods: Serum CK18 levels were measured using ELISA from 52 newly diagnosed breast cancer patients, at presentation and after first cycle of neo-adjuvant chemotherapy. Pre- and post-treatment CK-18 levels were correlated with several clinical and pathological parameters. At the end of neoadjuvant treatment, changes in serum CK18 levels were correlated with tumors’ response to therapy. Results: Significant elevation of pre-chemotherapy CK18 level was observed in patients who had progressive disease compared to those who had complete or partial response to therapy (P=0.006 and P<0.001, respectively). Significantly higher CK18 levels were observed post-chemotherapy in complete and partial responders, in contrast to patients with stable or progressive disease (P=0.012% and P=0.001%, respectively). The percent of change was significantly higher in complete responders compared to patients who had stable or progressive disease (P=0.043% and P=0.045%, respectively). Conclusion: Our results suggest that patients with increasing CK18 level following chemotherapy are potential responders to their neoadjuvant protocol. Thus, the measurement of serum CK18 early in the treatment course could be a simple, noninvasive way to predict tumor response to neoadjuvant chemotherapy.