Prevalence of high-risk human papillomavirus types (HPV-16, HPV-18) and their physical status in primary laryngeal squamous cell carcinoma.

Recently oncogenetic human papilloma virus(HPV) infection has been suggested to promote laryngeal squamous cell carcinoma(LSCC). To determine the prevalence and genotypes of HPV infection in laryngeal cancer specimens, 84 specimens from pathologically confirmed LSCC patients were studied for the presence of viral DNA and possible virus integration into the cellular genome. HPV genotyping was assayed prior to the integration analysis by using two PCR-based assays, including HPV-16 and-18 E7 type-specific and L1 general primers (GP5+/GP6+). Additionally, a quantitative real-time PCR (qRT-PCR) was used to examine the physical status of HPV-16 or-18 in HPV positive LSCC. Using HPV L1 general primer amplification, HPV DNA was detected in 23 (27.4%) of the 84 LSCC samples. When PCR products were cloned and sequenced, HPV16 were found in all 23 L1 positive samples. However, when specific primers for HPV- 16 or -18 were used to amplify E6 and E7 in all samples, 29 cases (34.5%) were positive for HPV-16, while 6 cases (7.1%) were positive for HPV 18. Coinfection of HPV-16 and -18 were found in 4 cases (4.8%). In addition, qRT-PCR assay found that HPV-16 was characterized as episomal in 51.7% of cases, mixed (i.e., episomal and integrated) in 34.5%, and integrated in 13.8%, while HPV-18 was similarly characterized as episomal in 83.3% of cases and mixed in 16.7%. In the present study, about 36.9% of patients with LSCC were found to be infected with HPV-16 and -18 and integration of HPV-16 and -18 DNA into the host genome was found.