Pleural CEA and C-reactive protein in patients with lung metastases and malignant pleural effusion. A prospective case-control study

Background: Malignant pleural effusion (MPE) is a common occurrence in lung cancer patients, especially in those with NSCLC, as well as in those with lung metastases (LMs) and pleural mesothelioma. MPE is usually suspected in patients with a history of malignancy and imaging studies showing indefinite pulmonary nodule(s). Unfortunately, most patients with LMs and pleural effusion (PE) require VAT-guided biopsy, because pleural fluid cytology has an overall low sensitivity. Thus, PF analysis is currently performed after thoracentesis to obtain further information. The aim of this study was to evaluate the diagnostic utility of pleural carcinoembryonic antigen (pCEA) and pleural C-reactive protein (pCRP) measurement in cancer patients with PE. Methods: We prospectively measured both pCEA and pCRP in 41 consecutive patients with a history of cancer and PE (cases) scheduled to undergo VAT-guided thoracentesis and biopsy, and 41 age- and sex-matched patients with confirmed benign PE (controls). There were 52 (63.4%) men and 39 (47.6%) women, with an overall median age of 71 years (range 40-88 years). Quantitative pCRP and pCEA measurement were obtained using a commercially available human CRP enzyme linked immunosorbent assay (ELISA) and a chemiluminescence immunoassay method (CLIA), respectively. The cut-off value pf pCEA was 5 ng/mL (pCEA) based on previously obtained data from laboratory archival information. Results: The age (cases vs. controls: 67.9\ub110.3 vs. 68.1\ub114.9 years, p=0.943) and male-to-female ratio (p=0.254) did not differ significantly between groups. Pleural CEA (34.9\ub1104.8 vs. 1.5\ub11.3 ng/mL; p