Abstract B21: Factors affecting outcomes in patients with squamous cell carcinoma of oropharynx
Authors: Nittala Mary R. , Bhanat Eldrin , Vijayakumar Srinivasn , Kanakamedala Madhava R. 
Published: September 2020

Objective: To study factors affecting outcomes such as overall survival (OS) and locoregional control (LRC), in patients with squamous cell carcinomas of oropharynx treated with definitive radiation therapy (RT), with or without concurrent chemotherapy.

Method: Retrospective analysis of 83 patients with squamous cell carcinoma of oropharynx treated with definitive radiation therapy at University of Mississippi Medical Center. All patients were treated to 70 Gy utilizing intensity-modulated radiation treatment. Stage III and IV patients also received concurrent chemotherapy with weekly cisplatin. Chi-square test was used to test the goodness of fit, OS and LRC comparing races were generated by using log rank test and Kaplan-Meier method. The covariables associated with the OS and LRC were determined by multivariate Cox regression model. Hazards ratio (HR) was used to estimate time to event outcome with associated 95% confidence intervals (CIs) and P values. Median follow-up for the entire group was 39 months.

Results: Of the total 83 eligible patients 51.8% were black, 48.5% were white, and 2.4% wee other. Stage distribution (per American Joint Committee on Cancer-AJCC 7th Ed) between blacks vs. whites for Stage I and II was 50% vs. 50%; for Stage III, 41.6% vs. 58.3%; and for Stage IV, 55.2% vs. 41.8%. In the univariate analysis, insurance, HPV/p16, body mass index (BMI), and race are the variables that affected the outcomes. In the multivariate analysis, HPV/p16, BMI, race, and tonsil subsite are shown to be significant. Age, gender, income level, employment, distance from facility, smoking, alcohol, and marital status are not shown to be significant. LRC for black patients was 49% vs. 72% in white patients (P = 0.022). Three-year OS for black patients was 49.2% vs. 66% for white patients (P = 0.010). HR for black patients was 0.13 with 95% CI 0.03- 0.61 (P= 0.009); HR for white patients was 0.24 with 95% CI 0.56- 1.06 (P= 0.061). OS for Stage IV black patients was 28% vs. 82% for white patients (P=0.006). In this cohort, HPV/p16 black positive patients were 75%, black negative 33%, white positive 87%, and white negative 50%, respectively. HR for HPV/p16 positive was 0.23 with 95% CI 0.07-0.71(P = 0.01). HR for tonsil subsite was 0.37 with 95% CI 0.15-0.91 (P=0.031). HR for BMI was 5.27 with 95% CI 1.79-15.5 (P = 0.003). The race, HPV/p16, BMI, and tonsil subsite were all independently associated with worse OS on multivariate analysis. HR for black patients was 0.16 with 95% CI 0.03-0.73 (P= 0.019), HR for HPV/p16 positive was 0.24 with 95% CI 0.07-0.73 (P = 0.013), HR for tonsil subsite was 0.41 with 95% CI 0.17-0.99 (P = 0.048), and HR for BMI was 5.59 with 95% CI 1.90-16.39 (P= 0.002). Race, HPV/p16, BMI, and tonsil subsite were all independently associated with worse locoregional failure on multivariate analysis.

Conclusion: Among all the covariables examined, race, HPV/p16 status, BMI, and tonsil subsite were shown to be affecting the locoregional and overall survival outcomes. Racial factor appears to be more significant in patients with Stage IV disease.

Citation Format: Mary R. Nittala, Eldrin Bhanat, Srinivasn Vijayakumar, Madhava R. Kanakamedala. Factors affecting outcomes in patients with squamous cell carcinoma of oropharynx [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B21.