Potential Utility of Serum Neuron-specific Enolase Levels in Small Cell Carcinoma of the Lung

To assess the value of neuron-specific enolase (NSE) as a possible biomarker of small cell lung cancer, serum levels were determined by radioimmunoassay in 93 newly diagnosed untreated patients and were compared to the NSE levels of 20 healthy adult controls [9.6 ± 0.7 (S.E.) ng/ml]. Serum NSE was elevated (>20 ng/ml) in 73% of all patients including 23 of 39 (59%) with limited-stage disease and 45 of 54 (83%) with extensive-stage disease. The mean serum NSE was significantly higher in extensive-stage disease (94.5 ± 13.8 ng/ml) compared to the mean value for limited-stage disease (33.7 ± 4.7 ng/ml) (p < 0.001). NSE was elevated in all patients with three or more sites of metastatic disease. Serial NSE determinations were obtained on 57 small cell lung cancer patients. NSE levels fell in 40 of 50 (80%) of patients responding to treatment, increased in 5 of 7 (71%) of patients with progressive disease, and increased in 30 of 35 (86%) of patients who relapsed. A persistent rise in serum NSE occurred as many as 12 weeks before the clinical recognition of relapse in 15 of 23 (65%) of patients for whom adequate serial NSE data were available. These findings indicate that serum NSE may be a useful marker for staging, monitoring treatment, and predicting relapse in patients with small cell lung cancer.