Human papillomavirus 16 E6 antibodies are sensitive for human papillomavirus–driven oropharyngeal cancer and are associated with recurrence

BACKGROUND: Human papillomavirus 16 (HPV16) E6 antibodies may be an early marker of the diagnosis and recurrence of human papillomavirus–driven oropharyngeal cancer (HPV-OPC). METHODS: This study identified 161 incident oropharyngeal cancer (OPC) cases diagnosed at the University of Pittsburgh (2003-2013) with pretreatment serum. One hundred twelve had preexisting clinical HPV testing with p16 immunohistochemistry and HPV in situ hybridization (87 were dual-positive [HPV-OPC], and 25 were dual-negative [HPV-negative]); 62 had at least 1 posttreatment serum sample. Eighty-six of the 161 tumors were available for additional HPV16 DNA/RNA testing (45 were dual-positive [HPV16–OPC], and 19 were dual-negative [HPV16–negative). HPV16 E6 antibody testing was conducted with multiplex serology. The following were evaluated: 1) the sensitivity and specificity of HPV16 E6 serology for distinguishing HPV-OPC and HPV16–OPC from HPV-negative OPC, 2) HPV16 E6 antibody decay after treatment with linear models accommodating correlations in variance estimates, and 3) pre- and posttreatment HPV16 E6 levels and the risk of recurrence with Cox proportional hazards models. RESULTS: Seventy-eight of 87 HPV-OPCs were HPV16 E6–seropositive (sensitivity, 89.7%; 95% confidence interval [CI], 81.3%-95.2%), and 24 of 25 HPV-negative OPCs were HPV16 E6–seronegative (specificity, 96.0%; 95% CI, 79.6%-99.9%). Forty-two of 45 HPV16–OPCs were HPV16 E6–seropositive (sensitivity, 93.3%; 95% CI, 81.7%-98.6%), and 18 of 19 HPV16–negative OPCs were HPV16 E6–seronegative (specificity, 94.7%; 95% CI, 74.0%-99.9%). Posttreatment HPV16 E6 antibody levels did not decrease significantly from the baseline (P =.575; median follow-up, 307 days) and were not associated with the risk of recurrence. However, pretreatment HPV16 E6 seropositivity was associated with an 86% reduced risk of local/regional recurrence (hazard ratio, 0.14; 95% CI, 0.03-0.68; P =.015). CONCLUSIONS: HPV16 E6 antibodies may have potential clinical utility for the diagnosis and/or prognosis of HPV-OPC. Cancer 2017;123:4382-90.