PRO-GASTRIN-RELEASING PEPTIDE(31-98) AS A TUMOR-MARKER OF SMALL-CELL LUNG-CANCER - COMPARATIVE-EVALUATION WITH NEURON-SPECIFIC ENOLASE

We attempted to clarify whether serum levels of a carboxy-terminal fra gment of ProGRP, ProGRP(31-98), could serve as a more accurate tumour marker in patients with SCLC than neuron-specific enolase (NSE). ProGR P(31-98) and NSE were measured retrospectively in 101 newly diagnosed untreated patients with SCLC, 111 with non-small-cell lung cancer (NSC LC) and 114 patients with non-malignant lung diseases. ProGRP(31-98) a nd NSE levels were determined using a sandwich enzyme-linked immunosor bent assay. Sensitivity in SCLC patients was 72.3% for ProGRP(31-98) a nd 62.4% for NSE. Comparing the area under curve (AUG) of 'receiver op erator characteristics' of ProGRP(31-98) with that of NSE, ProGRP(31-9 8) was the more powerful marker in the diagnosis of SCLC (P=0.0001). S erum levels of ProGRP(31-98) were higher in the 40 patients with exten sive disease than in the 61 patients with limited disease (P=0.0082). ProGRP(31-98) was significantly higher in patients with pure small-cel l carcinoma than in patients with mixed small-cell/large-cell carcinom a (P=0.02). In Serial measurement in 16 patients responding to treatme nt, a high degree of correlation was noted between the decrease in ser um ProGRP(31-98) levels and clinical response during the second week a fter treatment (P=0.0045). These results indicate that the determinati on of serum ProGRP(31-98) levels plays an important role in the diagno sis and treatment of SCLC patients.