FDG PET/CT imaging of oropharyngeal squamous cell carcinoma: characteristics of human papillomavirus-positive and -negative tumors.

OBJECTIVE: The objective of this study was to assess differences in morphological and glycolytic characteristics of primary tumors and locoregional nodal disease between human papillomavirus (HPV)-positive and HPV-negative oropharyngeal head and neck squamous cell carcinoma. METHODS: This was a retrospective analysis of 123 baseline FDG PET/CT scans from patients (aged 57.0 ± 10.6 years) with newly diagnosed oropharyngeal SCC between January 2003 and June 2012. There were 98 HPV-positive and 25 HPV-negative patients. SUVmax, SUVpeak, and SUVmean based on lean body mass, as well as RECIST (Response Evaluation Criteria In Solid Tumors) dimensions, metabolic tumor volume (gradient and threshold-segmentation methods) and total lesion glycolysis, were determined for primary and locoregional nodal disease. RESULTS: Human papillomavirus-negative primary tumors were significantly larger as measured by RECIST longest diameter (P = 0.002) and slightly more heterogeneous as measured by the heterogeneity index (P = 0.07), higher SUVmax (P < 0.01), SUVpeak (P = 0.01), SUVmean (P = 0.01), metabolic tumor volume (P = 0.002), and total lesion glycolysis (P = 0.001), for both segmentation methods. Index parameters of HPV-positive nodal disease tend to be larger, but some with no statistical significance (P > 0.05). There was no significant difference in the metabolic parameters of primary tumor or nodal metastases for HPV-positive patients with and without smoking history. CONCLUSIONS: Index morphologic and glycolytic parameters as measured in FDG PET/CT are significantly larger in HPV-negative as compared with HPV-positive primary oropharyngeal carcinoma. In contrast, the same parameters trended to be larger in HPV-positive regional nodal disease.