Detection of human papillomavirus in non-small cell carcinoma of the lung

High-risk human papillomavirus (hrHPV) is an etiologic agent in squamous cell carcinoma (SqCC) arising in the oropharynx and cervix, and a proven prognostic factor in oropharyngeal SqCC. Many studies have found HPV in non-small cell lung carcinoma (NSCLC). Recent studies advocate the detection of messenger RNA transcripts of E6/E7 as more reliable evidence of transcriptively active HPV in tumor cells. The clinical significance of finding HPV remains unclear in NSCLC. This study sought to determine the prevalence of biologically active HPV infection in NSCLC comparing different methodologies. Surgical pathology material from resected primary lung adenocarcinoma (ADC; n=100) and SqCC (n=96) were retrieved to construct tissue microarrays. In situ hybridization (ISH) for hrHPV DNA (DNA-ISH), hrHPV E6/E7 RNA (RNA-ISH), and p16 immunohistochemistry were performed. Cases of oropharyngeal SqCC with known HPV infection were used as positive controls. Expression of p16 was scored as positive if at least 70% of tumor cells showed diffuse and strong nuclear and cytoplasmic staining. Punctate nuclear hybridization signals by DNA-ISH in the malignant cells defined an HPV-positive carcinoma. Of the 196 patients (range, 33-87 years; 108 men), p16 was positive in 19 ADCs and 9 SqCCs, but HPV DNA-ISH and RNA-ISH were negative in all cases. Our study did not detect HPV infection by DNA-ISH or RNA-ISH in any cases of primary NSCLC despite positive p16 expression in a portion of ADC and SqCC. p16 should therefore not be used as a surrogate marker for HPV infection in NSCLC.