Neuron-specific enolase as a marker of brain metastasis in patients with small-cell lung carcinoma.

Neuron-specific enolase (NSE) is one of the iso-forms of enolase, a glycolytic enzyme found in the neuroendocrine system. NSE is one of the most widely used tumor markers in small-cell lung carcinoma (SCLC). To assess the value of NSE in discriminating between the sites of metastases in SCLC-patients with and without cerebral involvement, serial NSE determinations were performed. Serum NSE was elevated in 76% of the patients at initial diagnosis. The value did not discriminate between the extent of disease nor between the sites of extrathoracic disease. NSE levels declined significantly at restaging. A persistent, significant rise occurred in patients with relapse of their disease, regardless of the site of relapse. In patients with brain metastases with and without extracranial disease at relapse, the NSE increase was significantly smaller than in patients without intracranial involvement. These findings indicate that serial determination of serum NSE in SCLC-patients may be useful in monitoring tumor activity but not in predicting the site of metastatic disease.