[Malignant pleural effusion as the presenting site of cancer: comparison with metastatic pleural effusions from known cancers]

Few studies have focused on malignant pleural effusions as the presenting site of cancer. The aim of our study is to evaluate their proportion in the total number of malignant pleural effusions, to identify their causes and determine their prognosis.

Patients were selected retrospectively from the database of the Pathology Department of the University Hospital of Nantes (France), which contained only the patients in whom a diagnosis of malignant effusion was made as the result of cytology of pleural fluid or pleural biopsy, between January 1999 and December 2001. Pleural effusions as the presenting site of cancer (R group) and those metastatic from known cancer (C group) were identified by study of the clinical data.

Of 209 cases, the malignant effusion was presenting site of cancer in 85 patients. In this group (R), a male predominance was identified (sex-ratio 1.36 vs. 0.42 in group C, p<0.01). In order of frequency the causes were: lung cancer (31 cases), mesothelioma (18 cases), primary cancer unknown (15 cases), ovarian carcinoma (10 cases), lymphoma (5 cases) and other carcinoma (2 cases). In men lung cancer was the leading cause (42.8%); and in women its frequency was the same as ovarian carcinoma (27.7%). The median survival of these patients was 6.5 months.

Pleural effusions as the presenting site of cancer account for 41% of all malignant pleural effusions. Their causes are mainly lung cancer in men and lung and ovarian cancers in women.