Accuracy of high-risk HPV DNA PCR, p16(INK4a) immunohistochemistry or the combination of both to diagnose HPV-driven oropharyngeal cancer.

BACKGROUND: The incidence of high-risk human papillomavirus (hrHPV)-driven head and neck squamous cell carcinoma, in particular oropharyngeal cancers (OPC), is increasing in high-resource countries. Patients with HPV-induced cancer respond better to treatment and consequently have lower case-fatality rates than patients with HPV-unrelated OPC. These considerations highlight the importance of reliable and accurate markers to diagnose truly HPV-induced OPC. METHODS: The accuracy of three possible test strategies, i.e. (a) hrHPV DNA PCR (DNA), (b) p16(INK4a) immunohistochemistry (IHC) (p16), and (c) the combination of both tests (considering joint DNA and p16 positivity as positivity criterion), was analysed in tissue samples from 99 Belgian OPC patients enrolled in the HPV-AHEAD study. Presence of HPV E6*I mRNA (mRNA) was considered as the reference, indicating HPV etiology. RESULTS: Ninety-nine OPC patients were included, for which the positivity rates were 36.4%, 34.0% and 28.9% for DNA, p16 and mRNA, respectively. Ninety-five OPC patients had valid test results for all three tests (DNA, p16 and mRNA). Using mRNA status as the reference, DNA testing showed 100% (28/28) sensitivity, and 92.5% (62/67) specificity for the detection of HPV-driven cancer. p16 was 96.4% (27/28) sensitive and equally specific (92.5%; 62/67). The sensitivity and specificity of combined p16 + DNA testing was 96.4% (27/28) and 97.0% (65/67), respectively. In this series, p16 alone and combined p16 + DNA missed 1 in 28 HPV driven cancers, but p16 alone misclassified 5 in 67 non-HPV driven as positive, whereas combined testing would misclassify only 2 in 67. CONCLUSIONS: Single hrHPV DNA PCR and p16(INK4a) IHC are highly sensitive but less specific than using combined testing to diagnose HPV-driven OPC patients. Disease prognostication can be encouraged based on this combined test result.

HPV DNA genotyping, HPV E6*I mRNA detection, and p16INK4a/Ki-67 staining in Belgian head and neck cancer patient specimens, collected within the HPV-AHEAD study.

BACKGROUND: The main risk factors for head and neck cancer (HNC) are tobacco and alcohol use. However, an important fraction of oropharyngeal cancer (OPC) is caused by human papillomaviruses (HPV), a subgroup with increasing incidence in several western countries. METHODS: As part of the HPV-AHEAD study, we assessed the role of HPV infection in 772 archived tissue specimens of Belgian HNC patients: 455 laryngeal (LC), 106 oral cavity (OCC), 99 OPC, 76 hypopharyngeal (HC), and 36 unspecified parts of the head and neck. All specimens were tested for HPV DNA (21 genotypes); whereof all HPV DNA-positives, all HPV DNA-negative OPCs and a random subset of HPV DNA-negatives of the other HNC-sites were tested for the presence of type-specific HPV RNA and p16INK4a over-expression. RESULTS: The highest HPV DNA prevalence was observed in OPC (36.4 %), and was significantly lower (p < 0.001) in the other HNCs (OCC:7.5 %, LC:6.6 %). HPV16 was the most common HPV-genotype in all HNCs. Approximately 83.0 % of the HPV DNA-positive OPCs tested HPV RNA or p16-positive, compared to about 37.5 % and 44.0 % in OCC and LC, respectively. Estimation of the attributable fraction of an HPV infection in HNC was very similar for HPV RNA or p16 in addition to DNA-positivity; with 30 % for OPC, and 3 % for OCC and LC. CONCLUSION: Our study confirms the heterogeneity of HPV DNA prevalence across anatomical sites in HNC, with a predominance of HPV16 in all sites. The estimated proportion of HPV-driven HNC in Belgium, during the period 1980-2014, was 10 times higher in OPC compared to OCC and LC.