Comparisons of pulmonary neuroendocrine tumors (PNET) and other groups with ROC analysis in terms of progastrin-releasing peptide (ProGRP), neuron-specific enolase (NSE), adjusted NSE, chromogranin A (CgA), and squamous cell carcinoma antigen 1 (SCCA1) values. Here, GRP is linked to primitive neuroectodermal tumor.