High-risk HPV genotypes and P16INK4a expression in a cohort of head and neck squamous cell carcinoma patients in Singapore

// Louise Soo Yee Tan 1 , Petersson Fredrik 2 , Liang Ker 1 , Feng Gang Yu 1 , De Yun Wang 3 , Boon Cher Goh 4 , Kwok Seng Loh 1, 3 , Chwee Ming Lim 1, 3 1 Department of Otolaryngology-Head and Neck Surgery, National University Health System Singapore, Singapore 119228 2 Department of Pathology, National University Health System Singapore, Singapore 119228 3 Department of Otolaryngology, National University of Singapore, Singapore 119228 4 Department of Medical Oncology, National University Health System Singapore, Singapore 119228 Correspondence to: Chwee Ming Lim, email: chwee_ming_lim@nuhs.edu.sg Keywords: human papillomavirus, p16 immunohistochemistry, HPV DNA, head and neck squamous cell carcinoma, oropharyngeal squamous cell carcinoma Received: June 29, 2016      Accepted: November 09, 2016      Published: November 22, 2016 ABSTRACT Human papillomavirus (HPV), especially HPV16 genotype, is associated with oropharyngeal squamous cell carcinoma (OPSCC). We aim to determine the prevalence and characterize the high-risk (HR)-HPV genotypes in head and neck SCC (HNSCC) in a South-East Asian multi-ethnic society in Singapore and examine its prognostic significance. 159 HNSCC archival tissue samples were retrieved and tumour DNA was screened for 18 HR-HPV genotypes using a PCR-based assay (Qiagen, digene HPV genotyping RH test). P16 protein overexpression was identified using immunohistochemistry (IHC). Statistical correlation between clinical outcomes were performed between HPV-positive and negative HNSCC patients. Six HR-HPVs (HPV16, 18, 31, 45, 56, 68) were detected in 90.6% of HNSCC; and 79.9% had multiple HPV genotypes detected. HPV31 and HPV45 were the most prevalent (79.2% and 87.4%, respectively); and HPV16 was predominantly found in OPSCC ( p < 0.001). HPV-DNA PCR assay yielded a high sensitivity (96%) but low specificity (11%) when compared to p16 immunohistochemistry as the reference standard. P16-positive HNSCC was predominantly observed in OPSCC (73.7%; p = 0.005); and p16-positive OPSCC exhibited improved overall survival compared to p16-negative OPSCC ( p = 0.022). Similarly, smoking and alcohol consumption were poor prognostic factors of overall survival ( p = 0.007; p = 0.01) in OPSCC patients. HR-HPVs were identified in 90.6% of HNSCC patients using the HPV-DNA PCR assay. This test had a poor specificity when compared to p16 IHC; making it an unreliable detection technique in selecting patients for radiation dose de-escalation treatment protocol. P16-positive tumor was predominantly found in the oropharynx these patients demonstrated better overall survival than those with p16-negative OPSCC.