Sensitive MRD detection from lymphatic fluid after surgery in HPV-associated oropharyngeal cancer

To demonstrate lymphatic drainage fluid (lymph) has improved sensitivity in quantifying postoperative minimal residual disease (MRD) in locally advanced HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) compared to plasma, which can be leveraged for patient risk stratification. We prospectively collected lymph samples from neck drains of 106 HPV (+) OPSCC patients, along with 67 matched plasma samples, 24 hours after surgery. PCR and next-generation sequencing were used to quantify cancer-associated cell-free HPV (cf-HPV) and tumor-informed variants in lymph and plasma. Next, lymph cf-HPV and variants were compared to TMN stage, extranodal extension (ENE), and composite definitions of high-risk pathology. We then created a machine learning model, informed by lymph MRD and clinicopathological features, to compare with progression-free survival (PFS). We found that lymph variant and cf-HPV quantification, performed on samples collected 24 hours after surgery, reflect single- and multi-feature high-risk pathological criteria. Incorporating lymphatic MRD and clinicopathological feature analysis can stratify PFS early after surgery in patients with HPV (+) head and neck cancer.