Usefulness of Serum Tumor Markers, Including Progastrin-Releasing Peptide, in Patients with Lung Cancer: Correlation with Histology

Tumor markers have been extensively studied in lung cancer, reporting some relationship to the histology, but their clinical utility is not clear.ProGRP, CEA, SCC, CA 125, CYFRA 21-1 and NSE were studied prospectively in 155 patients with unconfirmed suspicion of lung cancer and in 647 patients with lung cancer: 182 squamous, 205 adenocarcinomas, 19 large-cell lung cancer (LCLC), 175 small-cell lung cancer (SCLC) and 66 unspecific non-small-cell lung cancer (NSCLC).Abnormal tumor marker serum levels were found in less than 5.3% of the patients with benign diseases, excluding CA 125 (21.3%). Tumor markers were related to histological type and tumor extension with significantly higher CEA (p <0.01) and CA 125 (p <0.007) serum levels in adenocarcinomas, SCC (p <0.0001) and CYFRA 21-1 (p <0.008) in squamous tumors and ProGRP (p <0.0001) and NSE (p <0.0001) in SCLC. Tumor markers may be useful in the histological differentiation of NSCLC and SCLC. Patients with SCC serum levels >2 ng/ml were always NSCLC, while those with SCC <2 ng/ml and ProGRP >100 pg/ml and NSE >35 ng/ml were all SCLC patients. The sensitivity was 76.7 and 79.5%, specificity was 97.2 and 99.6%, with a positive predictive value of 98.6 and 98.6% and a negative predictive value of 60.7 and 92.9% in the differentiation of NSCLC and SCLC, respectively.Tumor marker determination in patients with suspicious signs of lung cancer suggests, in a few hours, the histological diagnosis in the majority of lung cancer patients.