Trajectories of EBV DNA and identifying the potential long-term survivors in metastatic nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is highly incident in southern China. Distant metastasis is the leading cause of death in NPC patients. However, the phenotypical feature of this patient population is largely undefined. The current study aimed to categorize metastatic NPC patients into novel subgroups based on their EBV DNA trajectories. In this retrospective study, 446 eligible patients with metastatic NPC treated at Sun Yat-Sen University Cancer Center between 2012 and 2016 were analyzed. Using a mixture model analysis, we identified distinct trajectories based on longitudinal EBV DNA measurements. We evaluated their associations with metastatic NPC mortality using Cox regression analysis. The two-class trajectory model provided the best fit, in which 272 patients were classified as non-sustained EBV DNA class and 174 patients as sustained EBV DNA class. After a median follow-up of 60.8 months, the median OS was 61.7 months in the sustained EBV DNA clearance class versus 20.0 months in the non-sustained EBV DNA clearance class (P<0.001). Compared with patients in the non-sustained EBV DNA clearance class, patients in the sustained EBV DNA clearance class demonstrated superior PFS (HR, 3.238; 95% CI, 2.601-4.032; P<0.001). Forty-three patients experienced disease-free for longer than 36 months, defined as long-term survivors (LTS). Notably, 41 patients were presented in the sustained EBV DNA clearance class (95.3%), along with only 2 patients in the non-sustained EBV DNA clearance class. Collectively, we identified two EBV DNA trajectory sub-phenotypes of patients with metastatic NPC, providing more reliable survival information for physicians and patients during their informed decision-making process.