Exploring the Impact of Human Papillomavirus Status, Comorbidity, Polypharmacy, and Treatment Intensity on Outcome of Elderly Oropharyngeal Cancer Patients Treated With Radiation Therapy With or Without Chemotherapy.

Abstract

To explore the impact of tumor human papillomavirus (HPV) status, comorbidity, polypharmacy, and treatment intensity on overall survival (OS) of elderly oropharyngeal cancer (OPC) patients. All elderly (>70 years) OPC patients receiving definitive (chemo-) radiation therapy in 2000 to 2013 were reviewed. Charlson comorbidity index (CCI, comorbidity alone) and the comorbidity-polypharmacy score (CPS, comorbidity and medication) were calculated. Overall survival was compared between HPV-positive (HPV+) and HPV-negative (HPV-) cohorts. Multivariable analyses (MVA) incorporating either the CCI (MVA-CCI) or the CPS (MVA-CPS) identified survival predictors. Among 231 of 287 patients (80%) with p16 staining, 117 were HPV+ and 114 HPV-. Systemic treatments were administered in 48 patients (21%) (chemotherapy 17; epidermal growth factor receptor inhibitor 31). The distribution of CCI (P=.59), CPS (P=.23), and age (P=.50) were similar between HPV+ versus HPV- cohorts. Median follow-up was 4.3 years. The HPV+ patients had better 5-year OS (57% vs 32%, P<.001) versus HPV- patients. Multivariable analysis adjusted for T-/N-category confirmed that HPV+ status (MVA-CCI: hazard ratio [HR] 0.58, P=.01; MVA-CPS: HR 0.60, P=.02), Zubrod scale score (0-1) (MVA-CCI: HR 0.44, P<.001; MVA-CPS: HR 0.43, P<.001), and higher radiation therapy dose (MVA-CCI: HR 0.97, P=.001; MVA-CPS: HR 0.96, P<.001) were correlated with higher OS. A marginal inverse correlation between CPS and OS was observed in the entire cohort (HR 1.05, P=.05) and was stronger for the HPV+ cohort (HR 1.11, P=.02). Nonsignificant higher OS was also found with ≤20 pack-years of smoking (MVA-CCI: P=.10; MVA-CPS: P=.15) and with systemic treatments (MVA-CCI: P=.13; MVA-CPS: P=.19). No association with OS was found for CCI (P=.46). Elderly HPV+ OPC patients have longer survival than their HPV- counterparts. Lower Zubrod scale score and higher radiation therapy dose are associated with longer OS, whereas fewer smoking pack-years and systemic agents have nonsignificant associations. Comorbidity-polypharmacy score, but not CCI, is correlated with OS, especially in HPV+ patients, suggesting the potential importance of assessing polypharmacy in addition to comorbidity burden in this population.