[Evaluation of tumor markers in the management of small cell lung cancer].

Since the therapeutic strategy for lung cancer is based on a classification of small cell lung cancer (SCLC) and non-small cell lung cancer (non-SCLC), not only histological examination but also detection of the biological properties which distinguish cancer cell types are clinically important. In this context tumor markers play a useful role in the detection of biological properties of lung cancers. This study was designed to evaluate the specificity of tumor markers for SCLC and their contribution to clinical management. Among many tumor markers for which assay systems are available in clinical practice, neuron-specific enolase (NSE) was shown to be the most specific to SCLC. Average values of extractable NSE in SCLC tissues and cultured SCLC cell lines were significantly higher than those in non-SCLC and normal specimens. Immunohistochemical analysis demonstrated positive staining for NSE in most cases of SCLC. In clinical studies, a serum value exceeding 10 ng/ml was set as a positive level in tests. Elevated levels of this enzyme were observed in approximately 70% of SCLC and less than 20% of non-SCLC, all of which were at an advanced stage. Consecutive daily determinations of NSE during induction chemotherapy showed transient elevation immediately after the initiation of drug administration and a subsequent declines to the normal range in responders. Periodic surveys of NSE were useful for predicting relapse prior to imaging detection. The data indicated that NSE is a specific and useful marker in the management of lung cancer. SCLC with elevated serum NSE should be treated with intensive chemotherapy due to progression of the disease.