Are levels of pro-gastrin-releasing peptide or neuron-specific enolase at relapse prognostic factors after relapse in patients with small-cell lung cancer?

The purposes of this study were to assess the relationship of serum levels of pro-gastrin-releasing protein (ProGRP) and neuron-specific enolase (NSE) at relapse with survival after relapse and the response to salvage therapy and to assess whether serum levels of ProGRP and NSE at relapse are useful markers for detecting relapse earlier than are symptoms or radiographic findings in patients with small-cell lung cancer (SCLC). The subjects of this study were 103 patients with SCLC who had achieved a complete response (CR) or partial response (PR) to first-line chemotherapy. We retrospectively evaluated whether ProGRP or NSE increased earlier than symptoms or radiographic findings appeared, and the association between response to salvage therapy and levels of ProGRP or NSE at relapse. In addition, we evaluated the association between survival after relapse and clinical and demographic factors at relapse, including age, sex, response to first-line treatment, sensitivity to first-line treatment, stage, performance status (PS), and serum levels of ProGRP, NSE, and lactate dehydrogenase. At relapse, 69.3% of patients had elevated serum levels of ProGRP, 60.2% had elevated serum levels of NSE, and 81.3% had elevated serum levels of either ProGRP or NSE. However, almost all asymptomatic relapses were detected with radiographic studies. The rate of CR to salvage chemotherapy was significantly lower in patients with elevated levels of NSE (2.2%) than in patients without (26.7%; p=0.001). Univariate analysis showed that sensitivity to first-line treatment, serum levels of NSE, stage, and PS at relapse were prognostic factors for survival after relapse. Multivariate analysis showed that sensitivity to first-line treatment, serum levels of NSE, and PS at relapse were independent prognostic factors after relapse. In conclusion, serum levels of ProGRP and NSE at relapse are not useful markers for detecting relapse earlier than are symptoms or radiographic findings. On the other hand, the serum level of NSE at relapse is a useful predictive marker for CR to salvage chemotherapy and a useful prognostic factor after relapse in patients with SCLC who have achieved a CR or PR to first-line chemotherapy.