Clinical values for abnormal 18F-FDG uptake in the head and neck region of patients with head and neck squamous cell carcinoma

• Abnormal 18F-FDG uptakes in the head and neck (HN) region can be carefully interpreted as being index primary, second primary cancer (SP) or benign.
• 18F-FDG PET/CT identified 91.9% primary HN squamous cell carcinomas (HNSCC).
• The specificity and negative predictive value of 18F-FDG PET/CT for identification of SP were as high as 98.7% and 99.3%, respectively.
• Proper detection of primary tumors and SP in the HN region may promote appropriate therapeutic planning of HNSCC patients.

PurposeFluorine 18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) is used to identify index or second primary cancer (SP) of the head and neck (HN) through changes in 18F-FDG uptake. However, both physiologic and abnormal lesions increase 18F-FDG uptake. Therefore, we evaluated 18F-FDG uptake in the HN region to determine clinical values of abnormal tracer uptake.MethodsA prospective study approved by the institutional review board was conducted in 314 patients with newly diagnosed HN squamous cell carcinoma (HNSCC) and informed consent was obtained from all enrolled patients. The patients received initial staging workups including 18F-FDG PET/CT and biopsies. All lesions with abnormal HN 18F-FDG uptake were recorded and most of those were confirmed by biopsies. Diagnostic values for abnormal 18F-FDG uptake were calculated.ResultsAbnormal 18F-FDG uptake was identified in primary tumors from 285 (91.9%) patients. False-negative results were obtained for 22.3% (23/103) T1 tumors and 2.2% (2/93) T2 tumors (P < 0.001). Thirty-eight regions of abnormal 18F-FDG uptake were identified in 36 (11.5%) patients: the thyroid (n = 13), maxillary sinus (n = 7), palatine tonsil (n = 6), nasopharynx (n = 5), parotid gland (n = 2) and others (n = 5). Synchronous SP of the HN was identified in eight (2.5%) patients: the thyroid (n = 5), palatine tonsil (n = 2), and epiglottis (n = 1). The sensitivity and specificity of 18F-FDG PET/CT for identification of SPs were 75.0% and 98.7%, respectively.Conclusions18F-FDG PET/CT is a reliable method for tumor staging and identify SP in HN region, promoting appropriate therapeutic planning. Additional examinations may be required to identify superficial or small-volume tumors.