Molecular detection and typing of human papillomavirus in laryngeal carcinoma specimens

Human papillomavirus (HPV) DNA was detected in 32% of laryngeal carcinoma biopsy samples studied. The genotypes identified were high-risk types, the most frequent being HPV 16. Viral DNA was integrated into the host genome (genotype HPV 16), providing supporting evidence for a role of HPV in the carcinogenic pathway of laryngeal squamous cell carcinoma.

HPV has been detected in laryngeal lesions, both benign and neoplastic, with a variable frequency (8-60%). These viral agents have been proposed as an adjuvant or cofactor in head and neck carcinogenesis because of their oncogenic properties. The aims of this study were to identify HPV in laryngeal carcinoma samples and to describe the physical state of the viral genome, i.e. its integration to the host DNA.

Formalin-fixed, paraffin wax-embedded tumor samples from patients with newly diagnosed laryngeal carcinomas were collected. The HPV genome was identified using polymerase chain reaction (PCR) with primers complementary to the conserved region L1 (MY09-11). Genotyping was accomplished by restriction fragment length polymorphism. Samples positive for HPV 16 were assayed by PCR with primers complementary to region E2, interrupted during viral genome integration.

Ten of the 31 samples (32%) were positive for HPV DNA and all of the samples were positive for human beta-globin. The genotypes identified were HPV 16 (n=3), HPV 58 (n=2) and HPV 39, 45, 51, 59, 66 and 69 (n=1 for each). The three samples positive for HPV 16 had lost region E2, meaning that the viral DNA had been integrated into the host genome.