Plasma carcinoembryonic antigen and tissue polypeptide antigen levels in lung cancer: correlation with cell types and stage.

This investigation was carried out to evaluate the plasma CEA and TPA levels in normal subjects and in 140 patients with lung cancer: 116 patients with nonsmall cell lung cancer (NSCLC) and 24 patients with small cell carcinoma (SCLC). The CEA and TPA levels were determined simultaneously by radioimmunoassay. The cutoff limit of CEA was found to be 17 U/SORIN, and the cutoff of TPA was 99 U/L. TPA has shown a sensitivity almost twice that of CEA. The relationship between the mean values of CEA and TPA and the stages of NSCLC was statistically significant (P less than 0.01), whereas only the mean values of TPA significantly (P less than 0.05) correlated with extensive and limited disease in SCLC. The determinations of combined CEA and TPA levels (CEA X TPA) (P less than 0.001) correlated significantly with the stage of disease in patients with NSCLC; conversely, the use of CEA X TPA did not correlate with the stage of SCLC.