Background Patients with bronchial pre-invasive lesions represent a significant management challenge due to the risk of lung cancer both at the site of known dysplasia and at remote sites within their lungs. The role of combined positron emission tomography/CT (PET/CT) in those patients is unknown.

Aims To evaluate the diagnostic and clinical utility of 18F-FDG PET/CT in a surveillance programme for patients with pre-invasive endobronchial lesions. This was defined as the ability of abnormal 18F-FDG uptake to detect invasive bronchial carcinomas adjacent to known pre-invasive lesions or at remote sites in the lung. The prognostic value of 18F-FDG uptake at dysplasia sites was also assessed with surveillance. Can 18F-FDG uptake predict progression of pre-invasive lesions or cancer elsewhere?

Methods 39 patients with pre-invasive endobronchial lesions underwent 18F-FDG PET/CT examination prior to autofluorescence bronchoscopy. Pre-invasive lesions were classified as either high-grade (carcinoma in situ or severe dysplasia) or low grade (mild to moderate dysplasia). The degree of uptake of 18F-FDG was analysed without knowledge of the bronchoscopic or other clinical findings.

Results 8/39 patients (all with high grade dysplasia) had increased 18F-FDG uptake at known dysplasia sites. Of these 8 patients 1 had surgical resection of invasive carcinoma and two patients were diagnosed and treated as invasive cancer based on imaging and follow-up. Eight patients had 18F-FDG uptake at sites remote from known dysplasia; 2/8 patients had synchronous invasive lung carcinoma (pT1N0M0), 2/8 recurrent cancer in hilar and mediastinal nodes, and 4/8 patients had inflammatory uptake in lung, mediastinal or hilar nodes. During surveillance of up to 3 years, 3/5 patients with positive 18F-FDG uptake developed biopsy proven invasive cancer at site of dysplasia. 3/31 patients with negative 18F-FDG uptake developed invasive cancer at high grade dysplasia sites during surveillance. No low grade lesion showed 18F-FDG uptake or progressed to invasive cancer during surveillance.

Conclusions PET/CT was able to detect early synchronous cancers in patients with pre-invasive endobronchial lesions. PET/CT was also able to detect 18F-FDG uptake in a proportion of patients at known dysplasia sites suggesting adjacent or underlying occult invasive carcinoma.