Biological evidence for a causal role of HPV16 in a small fraction of laryngeal squamous cell carcinoma
A partir de 154 échantillons tumoraux inclus en paraffine et de 55 tissus congelés prélevés sur 102 patients, cette étude évalue l'association entre une infection par le papillomavirus humain de type 16 et le risque de carcinome épidermoïde du larynx
Background: Human papillomavirus (HPV) is a causal factor in virtually all cervical and a subset of oropharyngeal squamous cell carcinoma (OP-SCC), whereas its role in laryngeal squamous cell carcinoma (L-SCC) is unclear.
Methods: Formalin-fixed paraffin-embedded (N=154) and deep-frozen tissues (N=55) of 102 L-SCC patients were analysed for the presence of 51 mucosal HPV types. HPV DNA-positive (HPV DNA+) cases were analysed for E6*I mRNA transcripts of all high risk (HR)/probably/possibly (p)HR-HPV identified, and for HPV type 16 (HPV16) viral load. Expression of p16INK4a, pRb, cyclin D1 and p53 was analysed by immunohistochemistry.
Results: Ninety-two patients were valid in DNA analysis, of which 32 (35%) had at least one HPV DNA+ sample. Among the 29 single infections, 22 (76%) were HPV16, 2 (7%) HPV56 and 1 each (4%) HPV45, HPV53, HPV70, HPV11 and HPV42. Three cases harboured HPV16 with HPV33 (twice) or HPV45. Only 32% of HPV DNA+ findings were reproducible. Among HPV16 DNA+ L-SCC, 2 out of 23 (9%) had high viral loads, 5 out of 25 (21%) expressed E6*I mRNA and 3 out of 21 (14%) showed high p16INK4a and low pRb expression (all three HPV16 RNA-positive), immunohistochemical marker combination not identified in any other HPV DNA+ or HPV DNA-negative (HPV DNA−) L-SCC, respectively.
Conclusion: HPV type 16 has a causative role in a small subgroup of L-SCC (<5% in this German hospital series).