p16 Immunohistochemical Expression in Head and Neck Squamous Cell Carcinoma: Association With Prognostic Parameters.

Background p16 is a tumor suppressor gene, over expression of which is considered as a surrogate marker of oncogenic human papillomavirus (HPV) infection. Moreover, p16 over expression correlates with good prognosis in head and neck squamous cell carcinoma (HNSCC). In the present study, we aimed to evaluate the frequency of p16 overexpression in HNSCC in our setup and its association with clinicopathologic parameters. Methods We performed p16 immunohistochemistry (IHC) on 144 cases of HNSCC. Association of p16 overexpression with various clinicopathologic parameters including T-stage, N-stage, grade, recurrence status, and risk factors was evaluated. Results p16 over expression was noted in 22.9% (33 cases), while 21.5% (31 cases) were focal positive and 55.6% (80 cases) were negative for p16 over expression. On the basis of percentage of expression; > 70% p16 expression was noted in 4.9% (7 cases), 9% (13 cases) showed 51% - 70% p16 expression, 9% (13 cases) revealed 11%-50% p16 expression, while 77.1% cases revealed no expression or < 10% p16 expression. Significant association of p16 expression was noted with nodal metastasis and extranodal spread while no significant association of p16 was noted with other prognostic parameters and risk factors. Conclusion Our data revealed that high expression (> 50%) of p16 is low in oropharyngeal squamous cell carcinoma in our setup. These finding suggest a low prevalence of HPV as a cause of HNSCC in our population. Moreover, p16 expression was found to be associated with some good prognostic parameters like lack of nodal metastasis, however, no significant association was noted with overall disease-free survival.