Abstract A89: Racial disparity in p16 positive oropharyngeal squamous cell carcinoma
Authors: Oprea-Ilies Gabriela M. , Moore Charles , Giri Mylar Joseph , Page Andrew J. , Rereddy Shruti K. , Majmudar Bhagirath , Muller Susan 
Published: May 2015

Oropharyngeal squamous cell carcinoma (OPSCC) has become increasingly prominent. Studies have definitively established a causal relationship between HPV and squamous cell carcinoma of the oropharynx. Up to 95% of HPV positive OPSCC patients are also positive for p16 as determined by immunohistochemical (IHC) methods.

Previous research has indicated that HPV positive OPSCC patients have a more favorable prognosis. For this reason, p16 status is emerging as an important consideration during risk stratification when predicting OPSCC patient survival. The majority of studies indicating that p16+ OPSCC patient prognosis is improved are based on research designed to represent a general population.

This project examines the influence of p16 positivity on patient prognosis in a retrospective cohort population of 120 patients with OPSCC. Furthermore, this project examines whether these findings are present in different racial/ethnic groups, when other variables, such as disease stage, age, gender and smoking history are similar.

These results may lead to better disease management and tailoring treatment taking into consideration the HPV status in OPSCC.

Methods: A retrospective cohort of patients from our hospitals with OPSCC was studied. A database was formed to organize history and outcomes for each of the patients. Overall survival (OS) was measured based on months of survival from time of diagnosis to death. Censored data was used to consider patients followed for different lengths of time or lost to follow up. 120 patients, on whom p16 data was available were grouped in 60 African-American (AA) and 60 Caucasian (CA). The 2 groups were matched for stage of disease. Kaplan Meier survival curves were produced to compare OS between 60 AA (31 p16+, 29 p16 -) and 60 CA (35 p16+, 25p16-). The Cox Proportional Model was used in a multivariate analysis in comparing these 2 groups to control for gender, age, tobacco use history, stage of disease at diagnosis and the type of treatment received: radiation and chemotherapy. SPSS version 21 was used for final statistical analysis.

Results: CA patients, on univariate analysis showed improved overall survival in p16+ individuals (figure A1. p &lt;.0001). A multivariate analysis also indicated statistically significant differences between p16+ and p16- CA and showed improved survival for those that were p16 + (figure B1. p=.004).

AA patients did not show improved survival when p16 positive, by univariate analysis (figure C1. p=.612). A multivariate analysis supported these results by demonstrating that there were no significant overall survival differences between p16+ and p16- AA patients (figure D1. p = .645).

Conclusions:

1. This study is in concordance with existing data in the literature, showing improved survival for p16 positive patients only in this studied CA group.

2. However, the benefit of improved survival for p16+ OPSCC was unexpectedly lost in AA patients in this studied group and further studies need to be undertaken to better understand the apparently different disease development.

3. When treating patients with OPSCC racial/ethnic factors should be considered, in addition to p16 status.

Citation Format: Gabriela M. Oprea-Ilies, Charles Moore, Mylar Joseph Giri, Andrew J. Page, Shruti K. Rereddy, Bhagirath Majmudar, Susan Muller. Racial disparity in p16 positive oropharyngeal squamous cell carcinoma. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr A89. doi:10.1158/1538-7755.DISP13-A89