Analysis of Human Papilloma Virus 16/18 DNA and its Correlation with p16 Expression in Oral Cavity Squamous Cell Carcinoma in North-Eastern India: A Chromogenic in-situ Hybridization Based Study.

Abstract

The incidence of head and neck squamous cell carcinoma (HNSCC) is quite high in North Eastern India. Apart from the traditional risk factors like tobacco and alcohol consumption, human papilloma virus (HPV) is now considered an established causative agent. These HPV related tumour have a clinico-pathological profile that is quite divergent from conventional non-HPV related tumours. Association of HPV in oral cancers has not been explored in north-east India. Thirty-one patients with oral cavity squamous cell carcinoma (OSCC) on treatment from October 2010 to January 2013 were included in the study. Patients who received neo-adjuvant chemotherapy were excluded. HPV 16/18 DNA was evaluated using Chromogenic in-situ Hybridization (CISH). Presence of nuclear signals was taken as positive HPV expression. p16 was evaluated using immunohistochemistry and was considered positive if ≥ 80% of the tumour cells showed strong and diffuse nuclear/cytoplasmic immunostaining. The results were analysed using Fisher exact test and confidence interval was calculated where required. The study group age ranged from 30 to 80 years (median age- 54.2 years). The most common site was gum, with well differentiated squamous cell carcinoma being the most common histology. HPV 16/18 DNA was positive in 29% (95% CI: 13.03% - 44.97%) cases and had a clear tendency towards statistical significance with non-smoker cases (p=0.05), lymph node metastasis (p=0.05) and a significant correlation with p16 overexpression (p=0.04). There was no significant correlation with other clinico-pathological parameters. HPV 16/18 is associated with OSCC, commonly seen among non-smokers and may be related to nodal metastasis. So, HPV may be used as a prognostic factor in OSCC and p16 may be considered as a surrogate marker for HPV.