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).

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.

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).

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.