Evaluation of a panel of molecular markers for the diagnosis of malignant serous effusions

Our main goal was to evaluate a panel of molecular markers for the detection of cancer cells in serous effusions and to determine their value as an adjunctive reverse transcription-PCR (RT-PCR) test to cytologic examination.

One hundred fourteen serous effusions from 71 patients with tumors and 43 patients with benign diseases were subjected to RT-PCR for expression of carcinoembryonic antigen (CEA), epithelial cell adhesion molecule (Ep-CAM), E-cadherin, mammaglobin, mucin 1 (MUC1) isoforms MUC1/REP, MUC1/Y, and MUC1/Z, calretinin, and Wilms' tumor 1 susceptibility gene.

CEA, Ep-CAM, E-cadherin, and mammaglobin were specifically expressed in malignant effusions. The sensitivity of RT-PCR in cytologically negative malignant effusions was 63.1% combining CEA and Ep-CAM (with 100% specificity) and reached 78.9% adding MUC1/Y or MUC1/Z (with 93% specificity). In the whole population of effusions, the combination of cytology with RT-PCR of CEA and Ep-CAM yielded a 90.1% sensitivity, a specificity and a positive predictive value of 100%, and a 86% negative predictive value for malignancy. Adding MUC1/Y or MUC1/Z to the panel, the sensitivity was 94.5% with 93% specificity, 95.7% PPV, and 90.9% negative predictive value. Moreover, CEA and mammaglobin were specifically expressed in epithelial malignancies, and mammaglobin was mainly expressed in effusions from breast carcinoma (97.3% of specificity).

A combination of cytology and RT-PCR analysis of CEA and Ep-CAM significantly improved the detection sensitivity of tumor cells in serous effusions. RT-PCR analysis of CEA, Ep-CAM, and mammaglobin in serous effusions could be a beneficial adjunct to cytology for the diagnosis of malignancy.