Radiation therapy dose de-escalation compared to standard dose radiation therapy in definitive treatment of HPV-positive oropharyngeal squamous cell carcinoma

Abstract

BackgroundDespite existing evidence that human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) has a favorable prognosis compared to HPV-negative OPSCC, randomized studies have yet to report the effect of de-escalating radiation therapy (RT) dose for definitive treatment. The aim of this study was to assess the effectiveness of dose de-escalated RT (DDRT) vs. standard dose RT (SDRT) in patients with HPV-positive OPSCC. MethodsThis was an observational study using the National Cancer Database (Year 2010–2014) to identify patients who had HPV-positive OPSCC and were treated with definitive RT or chemo-RT. Patients undergoing surgery were excluded. Patients receiving ≥50 Gy, but <66 Gy were categorized as receiving DDRT. Patients receiving ≥66 Gy were categorized as receiving SDRT. Inverse probability of treatment weighting (IPTW) using propensity scores was used to balance the two groups. Kaplan–Meier analysis was used to estimate overall survival (OS). Subset analyses in patients receiving RT alone and concurrent chemo-RT were also performed. Multivariable Cox proportional hazards modeling was used to evaluate factors associated with OS. Results759 patients with HPV-positive OPSCC were identified: 104 received DDRT and 655 received SDRT. The median follow-up was 30.5 (2.4–81.4) months. After IPTW-adjusted analysis, there was no difference in the 3-yr OS between the two groups (82.2% vs. 79.3%; P = 0.85). In the subset of patients receiving concurrent chemoradiotherapy, IPTW-adjusted analysis also did not show a difference in the 3-yr OS between the two groups (83.1% vs. 79.6%; P = 0.83). On multivariable analysis, DDRT was not associated with an inferior OS (HR 0.88; 95% CI, 0.53–1.47; P = 0.63). ConclusionsIn this study, DDRT was not associated with an inferior OS compared to SDRT in patients with HPV-positive OPSCC. Randomized clinical trials to address DDRT in this patient population are currently ongoing.