Use of (18)F-Fluorodeoxyglucose Positron Emission Tomography in Patients with Rare Head and Neck Cancers

OBJECTIVES: The clinical utility of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been demonstrated in major head and neck cancers (HNCs) but is unclear in rare HNCs. We therefore evaluated FDG PET in the management of patients with rare HNCs. METHODS: FDG PET and CT/MRI scanning were performed at the initial staging and/or the follow-up in 24 patients with rare HNCs, 10 with melanoma, 9 with sarcoma, 3 with olfactory neuroblastomas, and 2 with basal cell carcinoma. The diagnostic accuracy of CT and FDG PET for detecting primary tumors and metastases were compared with a histopathologic reference. The association between the PET results and the clinicopathologic parameters predicting tumor invasion, histologic grade and disease-free survival (DFS), was assessed. RESULTS: The overall accuracies of FDG PET and CT/MRI were 92% and 79%, respectively, for detecting primary tumors and 91% and 74%, respectively, for nodal metastases, but the differences were not significant due to the small number of patients. The sensitivity and specificity of FDG PET for detecting distant metastases and second primary tumors were 100% and 87%, respectively. Follow-up FDG PET correctly diagnosed locoregional recurrence in all 12 patients, as shown by biopsy, and distant metastases in 6 patients. However, thickness of melanoma, histologic grade of sarcoma, and DFS were not associated with tumor FDG uptake. CONCLUSION: FDG PET may be useful for staging, posttreatment monitoring, and detection of distant metastases and second primary tumors in patients with rare HNCs.