Talc - Rationale and Use in Malignant Pleural Effusions

Abstract

Questions relating to drug use, dosing, and related issues in oncology are presented in this regular feature. IntroductionNeoplastic diseases account for approximately 13% of the annual incidence of pleural effusions, and 75% of these effusions are secondary to malignancies of the lungs and breast or lymphoma. 1 The most common pathogenic mechanisms that produce malignant pleural effusions (MPE) are (1) pleural metastasis resulting in increased membrane permeability beyond the capacity of lymphatic drainage, (2) metastatic disease of the lymphatic system resulting in decreased clearance of pleural fluid, (3) bronchial obstruction resulting in reduced pleural pressure, and (4) pericardial metastasis resulting in pleural fluid accumulation. 2 Although systemic chemotherapy is an option for treatment of patients with sensitive tumors, removal of pleural fluid followed by pleurodesis is the primary treatment of MPE. Chemical pleurodesis, also known as sclerosis or obliteration of the pleural space, involves instilling a sclerosing agent bleomycin, doxycycline, or talc -into the pleural space after fluid drainage.2 Tetracycline injection was one of the mainstays of treatment but is no longer available, and nitrogen mustard and quinacrine are now rarely used due to their side effects. 2 ApproachThe goal of management is to alleviate shortness of breath (the most common symptom of MPE), cough, chest pain, and tachypnea. Table 1 summarizes the characteristics of patients who are likely to benefit from chemical pleurodesis.Factors that govern the likelihood that a sclerosing agent will be effective are summarized in Table 2. 2 The intent of intrapleural administration of a sclerosing agent is thought to be the creation of a chemically induced, inflammatory pleuritis that forms adhesions between the parietal and pleural surfaces. This obliterates the pleural space and prevents fluid reaccumulation. 2 Some agents, however, do not cause pleuritis but control effusions. Prior to pleurodesis, the pleural fluid is drained by placing a chest tube, usually via the seventh or eighth intercostal space and into the pleural space connected to a water-sealed suction drainage system. 2 The position of the chest tube, the completeness of the drainage, and the re-expansion of the lung are monitored by chest radiography. [2][3][4] Inadequate drainage of the accumulated fluid may indicate poor tube placement, obstruction of the tube by fibrin or other debris, or loculations. The longer a chest tube is kept in place, the higher the risk of loculation formation. Loculations are pockets of pleural fluid entrapped by membranes of fibrin connecting the parietal and visceral pleura. Effective drainage of entrapped fluid may require the insertion of more than one chest tube. Fibrinolytic agents (eg, streptokinase, urokinase) are used occasionally to solubilize the membranes of fibrin. 2-5