[Gastrin-releasing peptide as a specific tumor marker in patients with small cell lung carcinoma, compared with neuron-specific enolase].

A sensitive radioimmunoassay (RIA) system for plasma gastrin-releasing peptide (GRP) was developed using immune-affinity chromatography for plasma extraction. Plasma neuron-specific enolase (NSE) levels were determined by use of RIA without extraction. Plasma GRP levels in 12 control subjects were (mean +/- SD) 1.2 +/- 0.26pg/ml. Plasma GRP levels were elevated at frequencies of 79% in untreated patients with small cell lung carcinoma (SCLC). The levels in 21 patients with non-SCLC were not elevated. In nine of 10 patients with complete response (CR) or partial response (PR), plasma GRP levels decreased significantly when the patients were judged to have achieved CR or PR. In four patients with progressive disease (PD), the levels were elevated after treatment when compared with levels before treatment. In six of 10 patients with CR or PR, plasma NSE levels decreased significantly at the judgment of CR or PR. In two of four patients with PD, the levels were elevated after treatment. Furthermore, changes in plasma GRP level showed more excellent correlation with the therapeutic response than changes in plasma NSE level in the clinical courses of two patients with CR and a patient with PD. These results suggest that the plasma GRP level could be a useful tumor marker in SCLC patients.