"HPV16 circulating tumour DNA for prognostic stratification and post-treatment surveillance in HPV-positive oropharyngeal cancer: A multinational study".
Abstract
Background
Improved biomarkers are needed to refine prognosis and enable earlier detection of recurrence in HPV-associated oropharyngeal cancer (OPC). We evaluated the diagnostic performance, clinical associations, prognostic value, and longitudinal surveillance utility of HPV16 circulating tumour DNA (ctDNA) in a multinational cohort including patients from South America and Europe.
Methods
Plasma samples from 173 patients with HPV-positive OPC from South America and Europe were analysed using droplet digital PCR targeting HPV16 E6. Twenty-seven HPV-negative OPC cases and 58 HPV-negative cancer-free controls were included to evaluate assay specificity. Associations with clinicopathological features, tumour burden, overall survival (OS), and disease-free survival (DFS) were assessed, including multivariable Cox models. Longitudinal post-treatment ctDNA surveillance was performed in 72 non-metastatic HPV-positive OPC cases.
Results
Baseline plasma HPV16 ctDNA demonstrated 100% specificity and 73.4% sensitivity for identifying HPV-positive OPC. Pretreatment ctDNA levels correlated with clinical stage and tumour burden and were detectable in 73.1% of stage I tumours. HPV-positive ctDNA-negative patients had significantly better OS than ctDNA-positive patients, and higher ctDNA levels (≥1082 copies/mL) predicted poorer OS. In multivariable models, higher ctDNA levels remained independently associated with worse OS (HR = 1.68; p = 0.019). ctDNA positivity further stratified patients with adverse clinical risk factors, with intermediate-risk ctDNA-positive cases showing worse OS (HR = 7.01; p = 0.0074). Persistent HPV ctDNA detection during surveillance was associated with disease progression or recurrence 6.3-23.0 months after completing treatment.
Conclusions
HPV16 ctDNA is a highly specific biomarker that reflects tumour burden and provides clinically meaningful prognostic information in HPV-associated OPC. Persistent post-treatment ctDNA detection was associated with disease progression, supporting the potential role of HPV16 ctDNA in risk-adapted surveillance following curative-intent treatment.