Lung cancer is the second commonest cancer in the UK with an incidence in 2006 of 37 100, and is the commonest cause of death from cancer, causing more than 33 000 deaths (22% of cancer deaths) each year.1 More than three-quarters of lung cancers fall into the histological category of non-small cell lung cancer (NSCLC). Currently, 10% of patients with NSCLC present with symptomatic brain metastases, and between a quarter and a third of those who initially survive radical treatment for stage III NSCLC will go on to develop brain metastases during their remaining life span.2 It is anticipated that over the next decade, an increasing proportion will develop brain metastases as adjuvant chemotherapy, concurrent chemoradiotherapy for locally advanced disease and chemotherapy for metastatic disease result in longer overall survival times.