Is the size of pleural effusion important in the study of patients whose first tumor manifestation is a pleural effusion

Backround: Malignant pleural effusion (MPE) accounts for 15-35% of all pleural effusions (PE) and may be the first manifestation of an oncologic disease. Objetive: To analyze the characteristics of patients whose cancer clinical debut was MPE, taking into account the size of the PE. Methods: Multicenter, retrospective study from April 2008 to April 2013. Cases with a malignant pleural cytology or histology were included. Patients who had previous cancer diagnosis were excluded. The size was stratified in relation to the percentage of affected hemithorax in the chest X-ray: mild (1-25%), moderate (26-50%), severe (51-75%) and very severe (76-100%). Epidemiological data, clinical features, pleural fluid characteristics, performed diagnostic procedures and histological type were analyzed. Results: 402 patients were studied, 60% men. Mean age was 70 (SD 12.9). The most frequent histology was adenocarcinoma, in 233 cases (58%). When analyzing the PE size we found 34% mild, 27% moderate, 22% severe and 17% complete affection of the hemithorax. Greater dyspnoea was present in patients with larger PE (p < 0.0001). Extra-thoracic symptoms were more frequent in the mild and moderate subgroups (p=0.0225). No differences were found among the appearance or characteristics of PE. Blind pleural biopsy was performed in 138 patients (34.3%), more frequently in the severe and very severe PE (p=0.0016). The size of PE did not influence the diagnostic tests performed or the histological type of tumor. Conclusions: MPE was at least moderate in most cases. Dyspnoea was more important in patients with greater PE, and extra-thoracic symptoms in smaller ones.