Tumours of the lung and mediastinum

Carcinoma of the bronchus is the commonest cancer in the Western world, having increased steadily in incidence since the 1930s. It spreads by local invasion and by lymphatic and haematogenous routes. Locally, the tumour may spread into the mediastinum or through the bronchial wall and lung parenchyma to the pleural space and chest wall. A great variety of tumours can arise in the mediastinum and tend to occur at different sites within it. The commonest malignant tumours of the anterosuperior mediastinum are thymomas and germ‐cell tumours, including teratomas of various types and seminomas. The incidence of mesothelioma is rising, presumably because of the widespread use of asbestos products. Crocidolite is thought to be the most carcinogenic fibre. Simian virus (SV)40 has frequently been found in mesotheliomas but the role of the virus as a cofactor in carcinogenesis is not established.