Human papillomavirus type 16 (HPV16) DNA copy number in oral rinse samples from oral cavity cancer patients

Objectives: The objective of this study is to examine the human papillomavirus type 16 (HPV16) DNA copy number in the oral cavity of cancer patients using oral rinse samples. Methods: We analyzed the HPV16 DNA copy number of oral rinse samples in 13 primary oral cavity cancer patients (mean age 67.8 years, range 48–84 years) who visited the Department of Oral and Maxillofacial Reconstructive Surgery of Hiroshima University Hospital (Hiroshima, Japan). The 13 oral cavity cancers included 6 carcinomas in situ and 7 squamous cell carcinomas. Real-time PCR analysis was performed to examine the number of HPV16 E6 viral copies in oral rinse samples. Additionally, the HPV16 integration status was investigated using the real-time PCR findings for HPV16 E2 genes in HPV16 E6-positive oral rinse samples. Results: HPV16 E6 copy numbers above the detection limit in a standard curve for HPV16 E6 DNA were assessed as HPV16 positive in oral rinse samples from 6 of 13 patients. The average number of HPV16 E6 viral copies was 1.71 ± 1.72 per cell (range, 0.39–4.96 copies/cell) in six oral rinse samples. The HPV16 E2 viral load was detected in four of the six HPV16-positive oral rinse samples. Two of the six HPV16-positive oral rinse samples showed HPV16 E2 copy numbers below the detection limit, indicating the full integration of HPV16 DNA. Conclusions: The number of patients in this study was small; therefore, further investigation using a larger number of participants is required to clarify the level of HPV16 viral copy number in the oral cavity of cancer patients.