Detection and quantitation of human papillomavirus (HPV) DNA in the sera of patients with HPV-associated head and neck squamous cell carcinoma

The human papillomavirus (HPV) has been implicated as an etiological factor in a subset of head and neck squamous cell carcinoma (HNSCC), Because circ ulating tumor DNA has previously been detected in the sera of patients with advanced HNSCC (stage III or IV), we hypothesized that HPV DNA might be pr esent in the sera of HPV-positive HNSCC patients. Serum DNA extracts from 7 0 patients with HNSCC were screened for HPV using conventional PCR and a re al-time quantitative assay. All samples subjected to conventional PCR were further tested hy dot blot hybridization, and positives were confirmed by S outhern blotting, Paired tumor DNA from archived tissues was then similarly screened for HPV genomic material (n = 51) or tested by in situ hybridizat ion (II = 19), HPV-16 DNA was detected with LI primers in 0 of 65 sera and In 15 of 70 (21%) tumors. Conventional PCR with E7 primers and Southern blo t hybridization detected HPV-16 DNA in four (6%) sera. Using real-time quan titative PCR, six samples were found to contain various levels of circulati ng HPV DNA (mean, 12 copies/ml; range, <1-35,) All sir serum-positive patie nts had corresponding tumors positive for E7, Four of these patients with H PV-positive tumors later developed distant metastases, suggesting that NPV DNA in serum may represent occult hematogenous spread of cancer cells in th is subset of patients, Although a much larger prospective trial is required , the presence of HPV genomic material in serum DNA of HPV-positive HNSCC p atients may serve as a useful marker of early metastatic disease.