The significance of NSE and CEA as a differentiation marker for the cellular heterogeneity of small cell lung cancer

Neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) levels in the culture supernatant of the 65 pulmonary carcinoma cell lines: Small cel l lung cancer (SCLC!) 18, large cell carcinoma 14, squamous cell carcinoma 14, adenocarcinoma 14 and adenosquamous cell carcinoma 5, were measured by a radioimmunoassay (RIA). The mean value of NSE was 30.8+/-22.4 ng/ml and 9 .2+/-8.7 ng/ml in SCLC and non-SCLC!, respectively. The mean value of CEA m as 15.1+/-20.9 ng/ml and 26.6+/-72.3 ng/ml in SCLC and non-SCLC, respective ly. A significant difference in NSE levels was obtained between SCLC! cell lines and non-SCLC cell lines. In SCLC cell lines, a significant inverse pr oportional correlation was observed between NSE and CEA levels. The CEA pro duction tended to be higher in cells with low levels of NSE than in those w ith high NSE production. With respect to correlation between marker product ion and growth characteristics of SCLC cells in vitro, significantly higher NSE and lower CEA levels mere found in cells growing with floating colony or neurite like characteristics (classic cell type) than those in cells wit h epithelial or intermediate growth characteristics (variant cell type). A significant positive correlation between NSE levels and the survival period s was found in follow-up studies of 10 patients who underwent surgery with complete resection of the primary tumor. All of 4 long term survivors over 3 years after surgery had significantly high NSE and relatively low CEA pro ducing tumors. The relationship of these markers to clinical status of the patient suggests that an analysis for correlation of NSE and CEA levels in SCLC patients may be useful to discriminate between a pure neuroendocrine S CLC tumor and a mined small cell/large cell tumor, and in monitoring therap eutic effect and prognosis of each patient.