Aim: To investigate the reduction in the serum level of cytokeratin-19 fragments (CYFRA 21-1), nucleosomes and neuron-specific enolase (NSE) as early measures of the response to chemotherapy in non-small cell lung cancer (NSCLC).
Methods: Forty-two consecutive patients with locally advanced NSCLC were included. All patients received platinum-based chemotherapy. Staging investigations and quantification of CYFRA 21-1, nucleosomes and NSE (using enzyme-linked immunosorbent assay, ELISA) were performed before the start of treatment and after the second cycle of chemotherapy. According to the response to chemotherapy, patients were classified into 3 groups: (I) disease regression, (II) stable disease, and (III) progressive disease. The reduction in the levels of tumor markers was correlated with the response to chemotherapy.
Results: After the second cycle of chemotherapy, groups I and II had significantly decreased serum levels of CYFRA 21-1 (p<0.05). Similarly, the concentration of nucleosomes was significantly lower than the baseline levels in groups I (p=0.0008) and II (p=0.003). The reduction of both CYFRA 21-1 and nucleosome levels was not significant for patients in group III. In all groups the reduction of NSE levels in response to chemotherapy was not significant. As a marker of response to chemotherapy, CYFRA 21-1 showed the highest sensitivity (88.9%) and specificity (77.4%) compared with nucleosomes (77.8% and 58.1% respectively) and NSE (66.7% and 51.8% respectively).
Conclusion: The reduction in the serum level of CYFRA 21-1 and nucleosomes may be used for early identification of NSCLC patients with good response to chemotherapy.