does the method of obtaining the cut-off point and reference population influence diagnostic yield?
OBJECTIVES: The aim of this study was to evaluate the clinical usefulness of the tumor markers CA125, CEA, NSE, SCC, and TPS in a group of patients with lung cancer. We estimated the influence of the method for choosing the cut-off point and of considering as a reference population either healthy controls or patients with some form of non-neoplastic pulmonary disease (NNPD). DESIGN AND METHODS: The tumor markers were determined using enzyme immunoassay techniques, and their diagnostic yield was evaluated using ROC curves and their correlation with the percentages between false and true positives. The diagnostic parameters of the tumor markers are presented in 116 patients with lung cancer and compared with a group of 25 healthy controls and another group of 80 patients with some form of NNPD. We determined on the one hand the cut-off points resulting from the best sensitivity-specificity balance in the ROC curves and on the other those resulting from considering a specificity of 95%. W
