Pro-gastrin-releasing peptide (proGRP) in patients with benign and malignant diseases: comparison with CEA, SCC, CYFRA 21-1 and NSE in patients with lung cancer.

We studied the specificity and sensitivity of progastrin releasing peptide (ProGRP) in 37 healthy subjects and 195 patients with benign and 149 with malignant diseases other than lung cancer. Likewise, we compared the ProGRP with other tumor markers used in lung cancer (CEA, SCC, CYFRA and NSE) in 187 patients with NSCLC and in 66 SCLC patients. We considered 50 pg/ml, 5 ng/ml, 2 ng/ml, 3.3 ng/ml and 20 ng/ml as the upper limits of normality for ProGRP, CEA, SCC, CYFRA 21-1 and NSE, respectively. Abnormal ProGRP serum levels were found in 10% of patients with benign diseases and in 13% of patients with malignancies other than lung. Renal failure was the main source of false-positive results (51.6%). Slightly raised ProGRP serum levels, excluding renal failure, were found in 4.1% of patients with benign diseases (<80 pg/ml) and in 5% of patients with malignancies other than lung cancer or neuroendocrine tumors (<120 pg/ml). Abnormal levels of ProGRP, NSE, CEA, CYFRA and SCC were found in 30%, 22.5%, 55.6%, 65.2% and 26.7% of NSCLC and in 73%, 64%, 53%, 46% and 4.5% of SCLC, respectively. Tumor marker serum levels were related to histological type and tumor extension, with ProGRP being the most sensitive marker in SCLC, CEA in adenocarcinomas and CYFRA 21-1 in squamous tumors. The most sensitive combinations of tumor markers were ProGRP and NSE in SCLC (88%), and CEA plus CYFRA in NSCLC (82%). In summary, ProGRP is the tumor marker of choice in SCLC and NSE is a complementary tumor marker in this histological type.