Positron-emission tomography for lung cancer in a tuberculosis-endemic region

A potential limitation of integrated positron-emission tomography and computed tomography in non-small-cell lung cancer may be false-positive results due to granulomatous disease. This retrospective study examined the accuracy of this imaging modality for mediastinal nodal staging of non-small-cell lung cancer in Hong Kong where tuberculosis remains endemic. There were 249 lymph node stations evaluated in 107 patients, of whom 38 (36%) had active tuberculosis or evidence of previous tuberculosis. Imaging results were compared with histological findings. The sensitivity, specificity, and accuracy of integrated imaging for mediastinal nodal staging were 52%, 86%, and 80%, respectively; the overall positive-predictive value for mediastinal nodal metastasis was 46%, and the overall negative-predictive value was 89%. The positive-predictive value for mediastinal nodal metastasis was 39% in patients with tuberculosis and 50% in controls; the negative-predictive value was high in both groups (92% and 87%). The likelihood ratio for true positives was 6.47 in patients with tuberculosis vs. 10.97 in controls. This suggests that the reliability of positron-emission/computed tomography may be substantially poorer in patients with tuberculosis. Histological confirmation should be considered mandatory in patients with suspected metastasis on integrated imaging.