Radiation-Induced Viral Activation in HPV-Associated Squamous Cell Carcinoma of the Oropharynx: A Prospective Analysis of Viral Expression in Saliva During Radiation Therapy

Abstract

distant metastasis-free survival (DMFS) were comparable between both treatment arms (HR: OS Z 1.05, 95% CI Z 0.44-2.53, p Z 0.915; DFS Z 0.77, 95% CI Z 0.44-1.35, p Z 0.362; DMFS Z 0.81, 95% CI Z 0.39-1.71, p Z 0.585). One hundred twelve patients had EBV DNA analysis pre-treatment (N Z 56, GCP and control). Of this group of patients, 37 (66.1%) and 41 (73.2%) in the control and GCP arms, respectively, had detectable levels of EBV DNA pre-treatment. For patients with detectable EBV DNA levels, induction GCP seems to confer a favorable DFS and DMFS (HR: DFS Z 0.39, 95% CI Z 0.141.11, p Z 0.056; DMFS Z 0.45, 95% CI Z 0.13-1.49, p Z 0.166). In contrast, DFS and DMFS were comparable between both treatment arms in patients with undetectable EBV DNA levels at baseline (HR: DFS Z 0.74, 95% CI Z 0.18-2.97, p Z 0.617; DMFS Z 0.80, 95% CI Z 0.115.69, p Z 0.864). Local regional failure rates were comparable between both arms, independent of baseline EBV DNA levels. Conclusions: The addition of induction chemotherapy to concurrent chemoradiation therapy in locally advanced NPC remains controversial. Nonetheless, patients with detectable EBV DNA levels pre-treatment appear to benefit from induction GCP, both in terms of DFS and DMFS. Baseline EBV DNA level potentially has a role as a predictive marker in stratifying patients with stage 3/4 NPC for induction chemotherapy. Author Disclosure: M. Chua: None. O. Whee Sze: None. J. Wee: None. Y. Soong: None. D. Lim: None. T. Tan: None.