(0610) Association Between Routine Laboratory Inflammatory Indicators and Circulating Tumor DNA Levels in HPV-Positive Oropharyngeal Carcinoma

Introduction: Inflammatory indices calculated from routine CBC with differential laboratories are being increasingly studied as indicators of cancer-related inflammation and have demonstrated prognostic utility in various non-head and neck solid tumors. This study aims to assess whether these inflammatory indices are associated with human papilloma virus (HPV) circulating tumor DNA (ctDNA) levels in pretreatment HPV-positive oropharyngeal squamous cell carcinoma (OPSCC).

Methods: Retrospective pilot study of HPV OPSCC patients with pretreatment levels of ctDNA (NavDx, Naveris Laboratories, Waltham, MA) identified from 2021-2023 at an academic hospital. ctDNA level group was classified as either “high” or “low” from the calculated median ctDNA level. Absolute cell counts from CBC with differential laboratories near the time of ctDNA lab draw were used to calculate four prognostic inflammatory indices: neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII = platelet * neutrophil/lymphocyte), and system inflammation response index (SIRI = neutrophil * monocyte/lymphocyte). Differences in characteristics—age, T-stage, and N-stage—between ctDNA level groups were assessed using Fisher’s exact and t-testing. Associations between high or low ctDNA level and inflammatory indices were assessed using two-sample t-tests.

Results: Pilot analysis included 16 patients who had pretreatment ctDNA and CBC with differential lab values. The median ctDNA level was 643.5 copies/μL. Age, T-stage, and N-stage were similar between high and low ctDNA patients (p > 0.05). High ctDNA levels, compared to low ctDNA levels, were significantly associated with higher average NLR (3.09 vs 1.75, p = 0.003) and higher average SIRI (1.54 vs 1.07, p = 0.04).

Conclusions: These pilot data suggest NLR and SIRI calculated from routine labs may be promising surrogate indicators of high HPV ctDNA levels in HPV-positive OPSCC. Further investigation is needed to explore this relationship and its potential impacts on prognosis and surveillance.