Neuron-specific enolase in the diagnosis of small-cell lung cancer with pleural effusion: a negative report.

We measured the concentration of neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) in the serum and pleural fluid of 53 patients with pleural effusions, including seven patients with small-cell lung cancer (SCLC). High levels (above 12.5 micrograms.l-1) of NSE in pleural fluid were observed in five patients with SCLC (sensitivity 71%). However, pleural fluid NSE levels were also increased in five patients with other types of cancer and in four patients with non-malignant inflammatory diseases (specificity 80%). We conclude that although SCLC with pleural effusion can be associated with elevated pleural fluid NSE activity, this increase in enzyme levels is not specific for malignancy.