Prognostic Factors in Patients with Malignant Pleural Effusion

should have specified whether such conditions were considered for exclusion before labeling the neutrophil-to-lymphocyte ratio as a prognostic variable. The initial volume of pleural fluid [3] , the associated radiological findings (e.g. extent of the primary tumor, associated lung collapse, involvement of central vessels and metastatic spread) and the cardiovascular comorbidities seem to us to be relevant prognostic variables which were not considered in the study. Lung cancer is the most common cause of malignant pleural effusion, having a maximum functional impact. It would be useful if the authors could conduct a subgroup analysis of lung cancer patients (including major histological types) to shortlist specific prognostic factors. The presence of malignant pleural effusion is in itself a bad prognostic sign which excludes the possibility of curative treatment. Prognostic factors associated with it should be interpreted with caution and no patient should be refused appropriate palliative treatment. We read with interest the study by Anevlavis et al. [1] in which they shortlisted 3 prognostic factors that determine survival in malignant pleural effusion. Certain points need discussion for better interpretation. The authors specifically enrolled patients in whom pleural effusion was the initial presentation of an underlying malignant disease. It is logical that such treatment-naive patients without any obvious primary tumor are more likely to have a better performance status, as was concluded in the study. However, an important group of patients was excluded, i.e. those who already had a histopathologically confirmed primary tumor and were secondarily found to have malignant pleural effusion. Secondly, pleural fluid in malignancy can also occur secondary to the enlargement of mediastinal lymph nodes and thoracic duct obstruction, which may not be picked up by thoracoscopy. Inclusion of these patient groups might have given different and more relevant results. The neutrophil-to-lymphocyte ratio was considered as an independent prognostic factor in the study. This ratio is a marker of systemic inflammation [2] and can be affected by past (<3 months) or present infection(s), hypertension, diabetes mellitus, renal or hepatic dysfunction, inflammatory diseases, etc. The authors Published online: June 14, 2014