Factors associated with false-positive staging of lung cancer by positron emission tomography

Background. Positron emission tomography imaging is gaining popularity as a noninvasive staging tool in non-small cell lung cancer. Nonmalignant proce sses can also affect radio-tracer uptake. This study seeks to identify fact ors associated with false-positive staging of mediastinal metastases. Methods. A retrospective review was performed of 100 patients with early st age non-small cell lung cancer referred for positron emission tomography sc an evaluation. All had pathologic confirmation of their disease. Positron e mission tomography scans, radiology records, operative reports, and patholo gy results were reviewed. Patients with positron emission tomography scans interpreted as positive for mediastinal involvement and negative pathology at operation were selected. Results. Seven patients were found to have a false-positive positron emissi on tomography evaluation for mediastinal metastases. All but 1 patient had a concurrent inflammatory process or an anatomic factor associated with the false positive. The sensitivity and specificity in detecting involved medi astinal nodes was 87.5% and 90.7%, respectively. The negative predictive va lue was 95.8%. Conclusions. Although positron emission tomography has been established as an accurate modality to stage non-small cell lung cancer, false-positive ev aluation of mediastinal metastases can occur in the setting of concurrent i nflammatory lung diseases or for centrally located tumors. Pathologic evalu ation of mediastinal disease should be pursued whenever suggested by a posi tive positron emission tomography scan especially in the face of those fact ors described. (C) 2000 by The Society of Thoracic Surgeons.