Neuron specific enolase, carcinoembryonic antigen and lactate dehydrogenase as indicators of disease activity in small cell lung cancer.

The clinical value of the three serum biomarkers neuron specific enolase (NSE), carcinoembryonic antigen (CEA) and lactate dehydrogenase (LDH) were evaluated prospectively in 86 patients with small cell lung cancer (SCLC) entered into randomized clinical trials. The patients were monitored clinically very closely and biomarkers were measured before each course of chemotherapy. The correlation between disease extent and biomarker was significant for both NSE (2P: 0.001) and LDH (2P:0.05). Of those two biomarkers NSE was the most sensitive and was raised in 75% of all patients at diagnosis, in 67% of patients with limited disease, and in 86% of patients with extensive disease. All patients with three or more sites involved presented raised serum NSE levels but there was no significant correlation between definite number or specific sites known to have metastatic disease. There was a tendency towards a higher serum CEA level in extensive disease than in local disease. Only half the patients with metastatic disease had elevated (greater than 5.0 ng/ml) levels of CEA, and values above 50.0 ng/ml were unusual. In patients initially seropositive for NSE a close correlation was found during follow up between serum NSE and response (98%) or progressive systemic disease (100%). During a major response, either complete or partial, serum NSE showed minor fluctuations (mean 8 ng/ml, S.D. 1.79, range 4.6-12.1). At present serum NSE seem to be the most sensitive and valuable biomarker in the management of SCLC, while the gain by adding CEA is small. Furthermore, NSE may be a useful tool in the estimation of disease extent and response to treatment in patients in whom clinical or radiological evaluation is difficult.