Malignant pleural effusion accounts for 22% of all pleural effusions, and affects about 300 000 patients annually (UK and USA). Approximately 50% of patients with breast cancer, 25% of those with lung cancer and >90% with pleural mesothelioma develop a symptomatic malignant pleural effusion. Thoracentesis provides effective short term symptomatic relief but most large malignant pleural effusions recur,1 and pleurodesis is then the standard treatment. A wide range of compounds have been used as pleurodesing agents, but talc is preferred by the majority of respiratory physicians worldwide.2

The Medicines and Healthcare Products Regulatory Authority (MHRA) has recently completed an urgent review of the safety of talc as a pleurodesis agent for malignant effusion, reclassifying it as a medicinal product rather than medical device.3 This review requires that from January 2008, manufacturers must submit regulatory data if they wish their talc preparation to be used for pleurodesis. This is a milestone on the path towards improved care for malignant effusion as it heralds the first time an agent for intrapleural administration will be regulated under the systems used for biologically active drugs.

Talc is a magnesium silicate hydroxide (Mg₃(Si₂O₅)₂(OH)₂) and is mined, milled and sterilised prior to clinical use, although these processes still sometimes leave behind mineral or organic contaminants. The MHRA review was a response to evidence that some of the preparations produced by these processes, and considered safe for pleurodesis in the UK and USA for over 50 …