Human papillomavirus DNA in squamous cell carcinomas of the larynx demonstrated by in situ DNA hybridization.

A series of 116 consecutive laryngeal squamous cell carcinomas were analyzed using an in situ DNA hybridization technique with 35S-labelled human papillomavirus (HPV) DNA probes to demonstrate the DNA of HPV types 6, 11, 16 and 30, in routinely processed, paraffin-embedded biopsies. The lesions were also assessed on light microscopy for HPV-suggestive morphological features, and by indirect immunoperoxidase (IP-PAP) technique to demonstrate the expression of HPV structural proteins (viral antigens). A total of 15/116 (12.9%) of the tumors were shown to contain the DNA of at least one HPV type. HPV 11 was the most frequent DNA type, found in 9/116 (7.8%) of the lesions, followed by HPV 16 (5.2%), and HPV 6 (4.3%). Noteworthy is the failure to disclose the recently described HPV type 30 DNA (suggested to be specific for laryngeal carcinomas) in any of the 116 carcinomas studied. Double infections (more than one HPV type) were disclosed in 5 (33.3% of the HPV DNA-positive) carcinomas: HPV 6 and 11, 1 case; HPV 6 and 16, 2 cases, and HPV 11 and 16, 2 cases. Light microscopic morphology was HPV-suggestive in 6 (40%) of the 15 HPV DNA-positive lesions, but HPV antigen expression could be demonstrated in one of these tumors only (6.7%). The present findings provide support to the concept on HPV as an etiological agent in laryngeal squamous cell carcinoma, most probably acting synergistically with chemical carcinogens. In addition to the 'high risk' HPV 16, a risk to develop a laryngeal malignancy may be associated with the 'low risk' types HPV 6 and 11 as well, previously demonstrated in benign laryngeal papillomas only.