Immunohistochemical expression of p16 in head and neck carcinoma.

Objectives: The aim of this study was to evaluate the immunohistochemical expression of p16 protein in cases of head and neck squamous cell carcinoma (HNSCC), and correlate with clinical data of patients.
Methods: Tissue samples (n=41) fixed in formalin and embedded in paraffin were obtained. The clinical variables of the patients were collected from medical records. Immunostaining for p16 was performed with “p16 CIN Tec® Histology Kit”. Immunohistochemical (IHC) expression was evaluated by three pathologists and scored as low (30%), high (greater than 30%) and no staining.
Results: Most patients were older than 55 and male. A total of 29 patients reported smoking and 22 consumed alcohol. The location of squamous cell carcinoma was in oral cavity for 22 patients and in oropharynx or larynx for 19. Concerning TNM classification, 22 patients had T3 or T4 tumors and 21 had metastatic lymph nodes (N+). Histopathological grade was well and moderately differentiated in 78% of the cases and 9 tumors were considered poorly differentiated. Expression of p16 resulted low in 8 cases, high in 4 and no staining in 29. Low expression of p16 was observed in most male patients with well or moderately differentiated oral tumors who had the habit of smoking and drinking. In cases of high IHC intensity of p16, 75% of patients were female and 100% of the cases presented well and moderately differentiated histologic grade. All clinical data correlated to p16 expression were P>0.05 (Fisher Test), it demonstrated that these associations were not significant.
Conclusions: In agreement with other studies, this study demonstrated that in most cases of head and neck squamous cell carcinoma the p16 is inactivated or presented low intensity.