Objectives and Background: Prognosis in patients with oropharyngeal cancer appears to be improved with HPV-related tumors, yet some patients that appear to be HPV-related still do poorly. The HPV E7 protein result in inactivation of pRB and thereby contributes to tumorigenesis. Our objective was to determine if additional prognostic information could be obtained from pRb staining in patients with oropharyngeal carcinoma.

Design: A retrospective cohort of all patients diagnosed with oropharyngeal squamous cell carcinoma (OPSCC) from 2006-2009 were identified. Immunohistochemical (IHC) staining for pRb was performed on tumor samples corresponding to patients within the cohort. Patients were stratified by p16 status as a surrogate for HPV positivity. Kaplan-Meier survival estimates, Cox proportional hazard regression models, and recursive partitioning trees were used for statistical analysis of the data.

Setting: Single tertiary care institution

Patients: Seventy two patients were identified with oropharyngeal cancer.

Main Outcomes Measures: Overall survival (OS) and disease free survival (DFS) were measured for each patient within the cohort, as were additional variables such as pRB status, age tobacco use.

Results: The Kaplan-Meier OS estimate for 2 and 5 year survival rate was 83.3% and 67.6%, respectively. DFS for 2 and 5 years was 76.9% and 73.8% respectively. The proportional hazards model found that pRb positive individuals had a decreased risk of both death (p=0.033) and recurrence (p=0.004) when compared to individuals who are pRb negative among both p16 positive or negative individuals. On recursive partitioning analysis within the p16 positive patients, there was higher risk of death of among the Rb negative tumors versus those who are pRb positive (p=0.004).

Conclusions: This study suggests that there is an increase in median OS and DFS in pRb positive OPSCC. pRB may offer additional prognostic in patients with OPSCC beyond currently used markers such as p16.