Accuracy of pleural carcinoembryonic antigen (CEA) assay in patients with benign and malignant pleural effusion requiring thoracentesis

Aim: Pleural effusion (PE) is a common condition, which recognizes various etiologies. Malignancies are a frequent cause of PE, but the diagnosis is often difficult, because positive cytology shows low sensitivity (50-60%). Several tumor markers have been tested in differentiating malignant from benign PEs, with the aim of avoiding invasive procedures. The aim of our study was to evaluate the usefulness of the pleural carcinoembryonic antigen (CEA) assay (PCEA) of patients with PE requiring thoracentesis. Methods: We measured PCEA in 106 patients (65 males, 41 females, mean age 68.5 ± 11.5 years) with PE who underwent videoassisted thoracoscopic (VATS) thoracentesis with minimally invasive biopsy, VATS or open pulmonary resection. The samples were assayed without any pretreatment or particular type of preservation with automated method of immuno-chemiluminescence (LOCI, Dimension Vista, Siemens HD, Camberry, UK). The cut-off used was 5 ng/mL. Results: Final pathologic evaluation showed 31 (29.2%) non-small cell lung carcinomas (NSCLC), 14 (13.2%) mesotheliomas, 26 (24.6%) metastases and 35 (33.0%) benign lesions. In PE suggesting malignancy (N = 71) the sensitivity of cytology was 57.7%. The PCEA was above the cut-off in 30/31 (96.8%) patients with NSCLC (1096.9 ± 398.9 ng /mL), 2/26 (7.7%) of metastases (31.6 ± 106.9 ng/mL), 1/35 (2.9%) of the benign conditions, and in none patients with mesotheliomas (1.1 ± 0.9 ng/mL). In patients with NSCLC, PCEA measurement was very sensitive (96.8%), while in those with benign lesions it was very specific (97.1%), resulting in an overall diagnostic accuracy of 97% (NSCLC vs. benign). Conclusions: Our results suggest that PCEA assay is effective, especially in differentiating NSCLC from benign lesions, and can be used in all patients with PE, potentially reducing the need for more invasive procedures.