Human papillomavirus type 16 oropharyngeal cancers in lymph nodes as a marker of metastases.

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 (<10(5) copies per million cells) in 8, and high (>10(5) 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.