Pro-gastrin-releasing peptide (ProGRP)--a useful marker in small cell lung carcinomas

Gastrin-releasing-peptide (GRP), the mammalian counterpart of amphibian bombesin, has been reported to be produced by cells of SCLC. Using recombinant ProGRP Yamaguchi et al developed an enzyme immunoassay for the measurement of this more stable precursor of GRP. We focused our interest on the comparability of ProGRP to neuron specific enolase (NSE), CYFRA 21-1 and CEA. For this purpose we investigated the sera of 272 patients with histologically proven carcinomas of the lung (87 SCLC, 185 NSCLC). The sera of 74 patients with benign diseases of the lung and smokers served as a reference group. At a specificity of 95% ProGRP and NSE possessed comparable sensitivities (47% versus 45%) in small cell lung carcinomas. ProGRP showed only a few more positive test results than NSE, but reached much higher value levels than NSE. ProGRP and NSE showed a clear additive sensitivity of about 20%. In NSCLC CYFRA 21-1 was the leading marker with 63% sensitivity, whereas ProGRP seldom showed a "false positive" test result. ProGRP proved a very high specificity and good sensitivity for small cell lung carcinomas and therefore enables diagnosis of small cell lung carcinoma in patients with lung tumours of unknown origin as well as good control of efficiency of therapy.