Role of whole body PET/CT in detecting distant metastasis in head and neck cancer

Full text: The incidence of distant metastases in patients with Head and Neck Cancers (HNC) is smaller ranging from 4 to 25%, with the lungs, bones and liver being the most frequent sites. 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)/Computer Tomography (CT) has shown more sensitivity in detecting unsuspected distant metastasis. Several reports indicate that for HNC a whole body may yield little additional information. So our aim was to evaluate the role of whole body PET/CT in detecting the distant metastasis in HNC. Materials and Methods: An analysis of 34 consecutive FDG PET-CT scans of head and neck cancers (Pharyngeal 3, Laryngeal 3, tongue 13, oral cavity 3, alveolar 2, maxillary sinus 1, tonsil 3, thyroid 4). Out of 34 patients, 19 were referred for initial staging and remaining 15 for restaging. Results: In staging group, FDG PET detected distant abnormalities in two patients in lung and adrenal. In restaging group, 2 patients were found to have distant metastatic lesions in lung, liver and bone was confirmed after biopsy. So therapy planning has been changed by whole body PET/CT in 1 during initial-staging and 2 during restaging. Conclusion: The detection of distant metastases at the time of initial evaluation and during restaging changes the prognosis and influences the selection of treatment modality in patients with HNC. While FDG-PET/CT had high sensitivity, specificity, and negative predictive value, it had a lower positive predictive value, suggesting that additional diagnostic methods are essential to rule out false positives and to avoid false upstaging to M1 for appropriate therapeutic planning