Lead Time to Recurrence After Posttreatment Plasma and Saliva HPV DNA Testing in Patients With Low-Risk HPV Oropharynx Cancer

IMPORTANCE Head and neck squamous cell carcinoma is a highly lethal cancer that is often associated with human papillomavirus (HPV). Recent studies have shown promise in the use of HPV DNA detection in salivary rinses and plasma as a factor associated with a future diagnosis of HPV-positive oropharynx cancer (HPVOPC). However, the use of plasma and salivary HPV DNA detection in defining risk for recurrence in the context of a prospective, phase 3, clinical trial coupled with standardized clinical surveillance has not been reported. OBJECTIVE To identify patients with low-risk HPVOPC at risk for recurrence by detection of HPV16 DNA in plasma and salivary rinses. DESIGN, SETTING, AND PARTICIPANTS In this cohort study, 233 low-risk patientswere recruited from 32 head and neck treatment centers in Ireland (1 [3.1%]), the Netherlands (1 [3.1%]), and the UK (30 [93.8%]) as part of the DE-ESCALATE HPV trial, an open-label, phase 3 randomized clinical trial examining treatment with cetuximab vs cisplatin for HPVOPC. Patients were assayed for the presence of HPV16 DNA in plasma and salivary rinse via a quantitative polymerase chain reaction-based assay. MAIN OUTCOMES AND MEASURES Assay resultswere associated with risk of recurrence and lead time from HPV16 DNA detection to recurrence. RESULTS Of 233 patients, 45 (19.3%) were women, and the mean (SD) age was 57.01 (8.45) years. A total 1040 salivary or blood samples were collected during the course of the study. With a median follow-up of 760 days, the sensitivity and specificity of combined plasma and salivary rinse HPV DNA assays for detecting recurrence were 65% and 87%, respectively. There was a median lead time of positive test to event/recurrence date of 19 days (range, 0-536 days) and mean (SD) of 122 (169.8) days. CONCLUSION AND RELEVANCE The results of this cohort study suggest that in the setting of a randomized, prospective, phase 3 trial for low-risk patients with HPVOPC, posttreatment presence of HPV DNA in plasma and salivary rinses is associated with recurrence; a lead time between test positivity and clinical recurrence offers a potential opportunity for earlier detection of recurrence.