Intraindividual homogeneity of ¹⁸F-FDG PET/CT parameters in HPV-positive OPSCC

¹⁸F-FDG PET/CT is widely used in clinical oncology. Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) represents an emerging disease that differs from HPV-negative OPSCC in clinical behavior and tumour biology. In these tumours, HPV-oncogenes might lead to distinct alterations in metabolic pathways. Therefore, we compared metabolic parameters using ¹⁸F-FDG PET/CT in HPV-positive and HPV-negative OPSCC in relation to histopathological findings.

Eighty-six patients with OPSCC received pre-therapeutic ¹⁸F-FDG PET/CT. Standardised uptake volume (SUV), total lesion glycolysis (TLG) and metabolic tumour volume (MTV) were analysed for the primary tumour. SUVmax was determined for neck lymph nodes. HPV-status was determined; overall survival rates (OS) were estimated.

32/86 patients (37.2%) had HPV-related OPSCC. Overall, PET-parameters in primary tumours of both groups did not differ significantly. Comparing early with locally advanced primary tumours, there was a significant increase in ¹⁸F-FDG uptake in HPV-negative patients (p<0.001). Positive nodes of HPV-related OPSCC showed significantly higher SUVmax values (p=0.039) compared to HPV-negative OPSCC. Strikingly, there was a higher intraindividual homogeneity of ¹⁸F-FDG uptake between primary and respective positive nodes in HPV-related primary OPSCC (p=0.001). SUV-max and -mean values did not correlate with OS in HPV-related OPSCC.

The intraindividual homogeneity of 18F-FDG uptake in HPV-related OPSCC could reflect the more homogenously, HPV-triggered carcinogenesis compared to the mutation-driven carcinogenesis in the HPV-negative OPSCC with heterogenic ¹⁸F-FDG uptake.