Background Oropharyngeal squamous cell carcinomas (OSCCs) are associated with high-grade human papillomavirus (HPV) infection in 20% to 30% of cases. HPV-16 DNA has been detected in cervical lymph node metastases of HPV-16+ OSCC. However, the meaning of HPV-16 DNA detection in lymph nodes remains controversial. Does the presence of HPV-16 DNA in lymph nodes correlate with their metastatic involvement, or is it just a consequence of the filter function of lymph nodes?
Methods Viral load quantification using reverse transcriptase–polymerase chain reaction was retrospectively performed in primary tumors and in cervical lymph nodes, originating from levels IIa, IIb, and III, in 11 patients with HPV-16+ OSCC and in 3 control patients with HPV-16− OSCC.
Results A total of 45 lymph node levels were analyzed. HPV-16 DNA was not detected in HPV-16− OSCC lymph nodes. No statistically significant difference was found between primary tumors and metastatic lymph nodes viral load (P >> .01). The viral load value was significantly higher in metastatic lymph nodes than in tumor-free lymph nodes (P < .01). Among 27 tumor-free lymph node levels, the viral load value was undetectable in 16, low or medium (<105 copies per million cells) in 8, and high (>105 copies per million cells) in 3.
Conclusions HPV-16 DNA detection in lymph nodes of patients affected with HPV-16+ oropharyngeal cancer is indicative of metastatic involvement. Tumor-free lymph nodes with a high viral load value would suggest the presence of occult lymph nodes metastasis and the opportunity to use HPV-16 DNA as a metastatic marker. Further investigations are needed.