Evaluation of a radioimmunoassay for neuron specific enolase in small cell lung cancer.

A radioimmunoassay for neuron specific enolase (NSE), a marker of neuroendocrine differentiation, has been evaluated in small cell lung cancer (SCLC). In untreated patients 25/38 (68%) with localized SCLC had raised blood levels of NSE (greater than 13 ng ml-1), in extensive disease 34/39 (87%) patients had raised NSE levels. In patients with non-small cell lung cancer (NSCLC) the serum levels were raised in 16/94 (17%). In extensive tumours of non-pulmonary origin NSE levels were increased in 24/116 (20%) patients. Longitudinal studies indicated a good correlation between the response to chemotherapy and fall of NSE levels. Tumour progression was accompanied by a rising NSE in 25/29 patients, with doubling times of 7-90 days. In patients with progression with a normal NSE the recurrence was a NSCLC. Cerebral metastases occurring as the only recurrence during clinical complete remission were not accompanied by a rise of NSE. Serum NSE levels provides a valuable monitor for SCLC during and after chemotherapy.