The value of follow-up FDG-PET/CT in the management and prognosis of patients with HPV-positive oropharyngeal squamous cell carcinoma

Introduction: To establish the accuracy of follow-up fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT and the impact of FDG PET/CT result on management decisions and patient outcome prediction (overall and progression free survival) in human papilloma virus (HPV)-positive oropharyngeal squamous cell carcinoma (SCC). Patients and Methods: We included 96 HPV-positive oropharyngeal SCC (OPSCC) patients with 254 follow-up PET/CT scans in the study. The PET/CT result accuracy was established with histopathology or 6-month clinical follow-up as reference standard. The impact on change in management was established for each follow-up PET/CT scan. Overall survival was evaluated using Kaplan–Meier plots with a Log-rank test. Results: The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the follow-up FDG-PET/CT were 97.0%, 92.5%, 67.0%, 99.5% and 93.1%, respectively. Follow-up PET/CT results were helpful in excluding tumour in 22% (9/41) of scans performed with prior clinical suspicion of disease and identified potential disease in 9.9% (21/213) scans performed without prior clinical suspicion. There was a change in management after 12.6% (32/254) scans. In 84.3% (214/254) scans, the patients were either observed or the same treatment was continued. The overall survival differed significantly between patients with a negative versus positive follow-up scan (log rank P < 0.001). The median progression free survival was 28 months, if the first follow-up scan performed within 6–12 months post-treatment completion was negative. Conclusion: Follow-up FDG PET/CT scans have an impact on the management plan and add value to clinical assessment in patients with HPV-positive OPSCC.