METHODOLOGICAL AND CLINICAL-EVALUATION OF 2 AUTOMATED ENZYMATIC IMMUNOASSAYS AS COMPARED WITH A RADIOIMMUNOASSAY FOR NEURON-SPECIFIC ENOLASE

We evaluated the clinical and methodological features of the neuron-sp ecific enolase radioimmunoassay (NSE RIA) (Pharmacia = Ph) with the ne uron-specific enolase enzyme immunoassay (NSE EIA) on the ES 700 (Boeh ringer Mannheim = BM) and the NSE EIA on the Cobas Core System (Roche = Po). A total of 253 serum samples obtained from 37 healthy persons, 45 patients with benign lung diseases, 124 patients with lung cancer ( 42 with small cell lung cancer, 23 with adenocarcinoma, 21 with squamo us cell carcinoma, 11 with large cell carcinoma, and 27 with unknown h istology), 34 with lung metastases, 7 patients with sarcoma and 6 pati ents with malign lymphatic diseases were stored at -80 degrees C and a ssayed retrospectively. The intra- and inter-assay imprecisions were l ower for the automatized test systems than for the RIA. Correlation be tween the EIA's and the RIA was better for NSE (Re) than for NSE (BM) (BM/Ph: r = 0.93 and slope = 0.54; Ro/Ph: r = 0.95, slope = 0.79), but weaker than the correlation between the two EIA's: over the whole ran ge r = 0.96, neuron-specific enolase < 50 mu g/l: r = 0.97, neuron-spe cific enolase < 20 mu g/l: r = 0.92. Fixing the specificity at 95% ver sus benign lung diseases we found a cut off value of 11.9 mu g/l for N SE RLA (Ph), 15.9 mu g/l for NSE EIA (BM) and 13.5 mu g/l for NSE EIA (Re). Based on this specificity of 95% versus benign lung diseases as the clinically relevant reference group, the sensitivity for NSE RIA w as 32% for all lung cancer and 45% for small cell lung cancer, for NSE EIA (BM) 35% for all lung cancer and 43% for small cell lung cancer, the NSE ELA (Re) had a sensitivity of 42% for all lung cancer and 57% for small cell lung cancer. In a follow-up study of two patients with small cell lung cancer a good comparability for all three assays in th e kinetics, but a marked difference in the neuron-specific enolase val ue levels was found. The results show that the NSE EIA (Re) on Cobas C ore system is the most sensitive assay for the detection of small cell lung cancer.