High P16INK4A Expression, Keratinizing Features, and Surgical Margin-Free Status are Associated with Improved Survival in Patients with Oral Squamous Cell Carcinomas.

Background: Oral squamous cell carcinoma (OSCC) continues to prevail as a highly prevalent cancer in Southeast Asia and causes a significant health burden. Stratification of patients with high risks of recurrence and mortality is important in the planning of treatment and surveillance.

Methods: Formalin-fixed paraffin-embedded (FFPE) tissues of OSCC were immuno-stained and analyzed for p16 expression. Risk factors and clinical parameters of OSCC patients were collected and compared to identify factors associated with recurrences and overall survival.

Results: After a median follow-up of 32 months, OSCC recurrences and mortality were observed in 82% and 78% of patients (N=60), respectively. Larger and more extensive tumors (T3 and T4) were significantly associated with both recurrences and cancer-associated mortality (OR = 3.967, 95% CI = 1.007-15.618 and OR = 5.885, 95% CI = 1.541-22.47, respectively). P16INK4A positive staining was found in 31% of tumors. Patients with p16INK4A positive staining were significantly associated with better recurrence-free and overall survivals (medians of recurrence-free survivals were 31.2 vs 19.0 months, P=0.038 and overall survivals were 39.0 vs 28.8 months,  P=0.048; respectively). Some other clinical characteristics including early stages, non-keratinizing tumors, negative cervical node, and free-surgical margin were significantly associated with better recurrence-free and overall survivals (log-rank tests, P<0.05).

Conclusion: P16INK4A positive staining, early stages, negative cervical lymph node infiltration, and free-surgical margins are associated with better prognosis in OSCC patients. The study emphasizes the importance of early detection and the potential use of p16INK4A and other clinical variables to stratify OSCC patients with high risks of recurrence and worse overall survivals.