Evaluation of p16 expression in oral and oropharyngeal squamous cell carcinoma

Oral and oropharyngeal cancers together are the 6^th most common cancers in the world and more than 90% are squamous cell carcinomas (OSCC, OPSCC). HPV is an important risk factor. p16 expression apart from indirectly assessing HPV infection, is an independent favorable prognostic marker. Lewis/Modified Lewis criteria of p16 grading identifies a subset of patients with improved overall survival.

(1) To evaluate p16 expression in these cancers. (2) To correlate p16 expression with age, gender, sub-site, histological type and grade. (3) To utilize the Lewis/modified Lewis criteria.

The study included 70 cases of OSSC's and OPSCC's. Histological features were analyzed. p16 expression was determined and graded. Results were analyzed and evaluated using Chi-square test (value of P < 0.05 was taken significant).

p16 positivity was seen in 46/70 (66%) cases (44 OSCC & 26 OPSCC). It was more frequent in younger patients and significantly higher in males. There was no correlation between degree of differentiation and p16 expression. In OSCC, 72.7% were p16 positive, mostly from tongue, buccal mucosa, and hard palate. p16 positivity was seen in 53.8% of OPSCCs, mostly from base of tongue and tonsil. Also, 30.4% of all cases could be included in Lewis criteria and 39.1% in modified Lewis criteria.

p16 is an inexpensive, easily available marker, it may be incorporated routinely in all histologically diagnosed cases of OSCC and OPSCC.