DIFFERENTIATION OF ADENOCARCINOMA OF THE LUNG AND MALIGNANT MESOTHELIOMA - PREDICTIVE VALUE AND REPRODUCIBILITY OF IMMUNOREACTIVE ANTIBODIES

A panel of antibodies against keratins, epithelial membrane antigen (E MA), epithelial antigen (Ber-EP4), carcinoembryonic antigen (CEA), tum our-associated glycoprotein (B72.3), vimentin and LeuM1 was applied to sections of adenocarcinoma of the lung and malignant mesothelioma in a randomized design. The proportion of stained tumour cells within eac h section was estimated independently in five categories by three path ologists (no positive tumour cells, 1-10%, 11-33%, 34-66% and more tha n 67% positive tumour cells). The kappa values representing the chance corrected interobserver agreement for the different antibodies in suc h a five group assessment were between 0.38 and 0.72. In two group ass essment the kappa values were between 0.53 and 0.94. Nosological sensi tivity and nosological specificity were calculated for all antibodies, and diagnostic sensitivity and diagnostic specificity (predictive val ues) were calculated for the Ber-EP4, CEA, B72.3, LeuM1 and vimentin. The difference between nosological sensitivity and nosologic specifici ty and the clinically relevant predictive values of positive and negat ive tests were demonstrated. In respect of the reproducibility and the diagnostic power defined by the predictive values, we demonstrated th at a panel of antibodies, including CEA, Ber-EP4 and B72.3 and, to a l esser degree, LeuM1 and vimentin is applicable for the histopathologic al distinction between adenocarcinoma of the lung and malignant mesoth eliomas. Before introduction of new diagnostic tests, including new an tibodies, the prevalence of the tested tumours should be estimated. No sological sensitivity and nosological specificity should be converted to predictive values.