Evaluation of serum neuron-specific enolase as a tumor marker for carcinoma of the lung.

Serum neuron-specific enolase (NSE) was measured in 80 normal subjects, 20 patients with small cell carcinoma of the lung (SCCL) and 54 patients with non-small cell carcinoma (non-SCCL). The mean value in the control group was 2.1 +/- 0.4 ng/ml (range, from 1.3 to 3.0 ng/ml). Serum levels exceeding 7.5 ng/ml were tentatively defined as positive. Thirteen of 20 patients (65%) with SCCL had positive serum NSE levels, whereas 6 of 54 patients (11%) with non-SCCL had positive levels. Positive NSE in sera of patients was observed only in patients with advanced clinical stage of SCCL or non-SCCL. No correlation between serum NSE levels and metastatic sites could be found. The serum NSE levels in subtypes of SCCL were positive in 9 of 10 patients with oat cell carcinoma and 4 of 10 patients with intermediate cell carcinoma. Histological types of all positive cases with non-SCCL included large cell carcinoma. Serum NSE levels changed in parallel with the clinical course during the treatments. The data suggested that serum NSE may be a useful marker for monitoring the clinical course of lung carcinoma, especially of SCCL. Furthermore, the detection of NSE in non-SCCL is of interest in relation to the histogenesis of lung carcinomas which exhibit the properties of neuroendocrine tumors.