Etiology of Pleural Effusions in Cancer Patients

ABSTRACT

PURPOSE: The purpose of this study is to examine the causes of Pleural effusion (PE) in cancer patients and to compare the clinical characteristics between malignant PE (MPE) and non-MPE. METHODS: All consecutive cancer patients with PE who underwent diagnostic thoracentesis from January 1, 2008 to March 31, 2011 were analyzed retrospectively. RESULTS: A total of 719 patients were included; mean age was 58.4+/-13.6 years and 44.5% were female. The most common cause of PE was MPE (57.7%), followed by parapneumonic or empyema in 16.3%. However, the etiology was significantly different according to primary tumor origin and subtypes of lung cancer. While MPE was most common in lung, breast, and gynecologic cancer, hepatic hydrothorax was the main cause in Hepatocellular carcinoma (HCC). MPE accounted for 85.2% in adenocarcinoma, and 30.2% and 58.8% in squamous cell and small cell carcinomas, respectively. Patients with MPE were younger (57.0 vs. 60.2 years) and female-dominant (55.4% vs. 29.6%) compared to those with non-MPE. MPE had the large size (53.5% vs. 34.9%) and left location of PE (31.3% vs. 19.4%) more frequently than non-MPE, and fewer neutrophils (15.4% vs. 30.6%) and more lymphocytes (32.2% vs. 28.2%), higher levels of pH (7.33 vs. 7.29), and lower levels of glucose (111.5 vs. 129.7 mg/dL) than non-MPE (p<0.001 for all). CONCLUSION: Overall, MPE was the most common cause of PE in cancer patients. However the etiology of PE was significantly different according to primary tumor origin and subtypes of lung cancer. A difference in age, gender, size and location of PE, cell count, pH, and glucose was observed between MPE and non-MPE.