A diagnostic model to detect silent brain metastases in patients with non-small cell lung cancer

We aimed to discriminate subgroups according to the risk of brain metastases in patients with non-small cell lung cancer (NSCLC) lacking neurological symptoms. We performed a retrospective review of 433 patients with NSCLC who underwent chest computed tomography (CT), brain magnetic resonance imaging (MRI) and bone scans at an initial staging work-up between April 2003 and April 2007. Brain metastases were determined by MRI. Patients were stratified into groups according to the number of risk factors (0–3) identified by multivariate analysis. In multivariate analysis, histopathology with non-squamous cell carcinoma, nodal stage ⩾2 on CT and presence of bone metastases were three risk factors for brain metastases. Patients were divided into four groups according to the number (0–3) of these predictive factors. The proportions of patients with brain metastases in the four groups were 2%, 3%, 17% and 35%, respectively, and these differences were significant (P < 0.001). When analysis was performed in patients with localised disease, the number of risk factors was correlated with the prevalence of brain metastases (P = 0.013) but stage was not (P = 0.153). Although this diagnostic model should be validated through further studies, our data suggest that the number of risk factors might be a useful tool to identify silent brain metastases in patients with NSCLC.