Pleural effusion is a common clinical entity affecting approximately 1.5 million patients per year in the United States. {3.1}A large number of diseases may be associated with pleural effusion.~This includes:~Local conditions affecting the pleura (eg, tuberculous pleurisy, pleural mesothelioma),~Extrapulmonary diseases with secondary pleural involvement (eg, chronic heart failure, liver cirrhosis).~To date, differentiation between both types of pleural effusion (exudate and transudate) is the most common initial diagnostic approach for patients with pleural effusion.~Exudative effusion is commonly seen in three conditions namely cancer (MPE), tuberculosis (TB) and para pneumonic Although MPE can be diagnosed by simple pleural fluid cytology, this method has significant limitations, including a highly variable sensitivity, ranging from as low as 11.6% to as high as 71%.~In contrast to other common causes of pleural effusion such as T.B, no accurate biomarkers of MPE have been established.~Several tumor markers were extensively evaluated, including carcinoembryonic antigen, cytokeratin-19 fragments, and cancer antigen 125, but none of them were found sensitive and specific enough to be implemented in routine clinical practice
To evaluate the ability of cancer ratio and pleural fluid markers to discriminate between malignant and non malignant effusion