Positron emission tomography in the evaluation of synchronous lung lesions in patients with untreated head and neck cancer.

Background: Positron emission tomography (PET) with the glucose analogue fludeoxyglucose F 18 uses the increased glucose uptake that is observed in neoplastic cells. It can differentiate between benign and malignant pulmonary lesions in patients with lung tumors. Applications of PET in extracranial head and neck neoplasms have included evaluating patients with unknown primary lesions, detecting primary and recurrent head and neck tumors, monitoring response to radiotherapy, and evaluating the N0 neck in oral cavity carcinomas. Its role in determining the presence of synchronous lung lesions has not been defined.

Patients And Methods: A retrospective review of 115 patients who underwent PET between October 1994 and October 1996 was performed to evaluate extracranial head and neck neoplasms. Fifty-nine (51%) previously untreated patients with squamous cell carcinoma of the upper aerodigestive tract were analyzed.

Results: Fifteen patients (25%) had PET scans that were positive for synchronous lung lesions. Five patients had a disease process that did not warrant further investigation; they did not have pathological confirmation of their lung lesions. Of these, 3 died of disease within 2 months of the diagnosis of primary head and neck squamous cell carcinoma, 1 was unavailable for follow-up, and 1 had lung lesions that were considered metastatic and no pathological confirmation of lung lesions was obtained. The remaining 10 patients with positive PET scan findings were investigated further: 8 patients had biopsy-confirmed lung lesions; 5 patients had positive findings on chest x-ray films; 8 had positive findings on computed tomographic scans; and 3 had positive findings on bronchoscopy. The results of 2 PET scans were false-positive. The PET scans were important in altering treatment in 3 patients; of these, 3 had negative findings on chest x-ray films, 2 had positive findings on computed tomographic scans, and 1 had positive findings on bronchoscopy.

Conclusions: The overall sensitivity, positive predictive value, and accuracy of PET were 100%, 80%, and 80%, respectively. The overall accuracy of radiography of the chest, computed tomography of the chest, and bronchoscopy was 70%, 90%, and 50%, respectively. The accuracy of PET over bronchoscopy was statistically significant (P<.05). PET appears to be a promising imaging modality for the detection of synchronous lung lesions in patients with negative findings on chest x-ray films.