False-negative findings for primary lung tumors on FDG positron emission tomography: staging and prognostic implications.

OBJECTIVE: The aim of this study was to determine the stage and outcome of patients with primary lung tumors who had a negative finding on a FDG positron emission tomography (PET) study at the time of diagnosis.
MATERIALS AND METHODS: A total of 3912 patients between November 1994 and August 2002 underwent thoracic or whole-body PET performed at our institution for evaluation of a pulmonary abnormality suspicious for lung cancer. We identified 20 patients with a biopsy-proven primary lung tumor and a negative PET study at the time of presentation. Surgical, pathologic, radiographic imaging, and clinical follow-up information were reviewed to confirm the histology, stage, and outcome.
RESULTS: Tumor histology included adenocarcinoma (n = 7, 35%), bronchioalveolar cell carcinoma (n = 6, 30%), carcinoid (n = 3, 15%), squamous cell carcinoma (n = 2, 10%), otherwise unspecified non-small cell lung cancer (n = 1, 5%), and sarcomatoid neoplasm (n = 1, 5%). One patient with bronchioalveolar cell carcinoma had multifocal stage IV disease, and all other patients were stage IA (n = 14, 70%) or stage IB (n = 5, 25%). Eighteen (90%) of the 20 patients underwent curative surgical resection. No patient is known to have tumor recurrence after resection, and three (17%) of the 18 patients are known to be living and free of disease 5 years after surgery.
CONCLUSION: With the exception of bronchioalveolar cell carcinoma and carcinoid, newly diagnosed lung cancers with negative PET findings are usually early-stage diseases and are associated with a favorable prognosis, suggesting that indeterminate pulmonary nodules, which are PET-negative, can be managed conservatively with serial radiographic studies to monitor for signs of growth. These findings warrant further study and should be confirmed with sufficient follow-up in a large cohort of patients with PET-negative lung lesions.