Table 1

Multivariate Cox regression analysis of peripheral blood cell Epstein-Barr virus DNA loads in all patients

Characteristics	Overall survival^a			Progression-free survival^a			Distant metastasis-free survival^b			Recurrence-free survival^b
Characteristics	n./N.	HR (95%CI)	P	n./N.	HR (95%CI)	P	n./N.	HR (95%CI)	P	n./N.	HR (95%CI)	P
≤ 392 copies/10⁶ globin	269/752	Reference	–	294/752	Reference	–	115/752	Reference	–	90/752	Reference	–
392–581 copies/10⁶ globin	49/104	1.50 (1.10–2.05)	0.010	54/104	1.50 (1.12–2.01)	0.007	20/104	1.31 (0.81–2.14)	0.272	12/104	1.05 (0.56–1.96)	0.889
581–918 copies/10⁶ globin	51/103	1.52 (1.12–2.07)	0.007	54/103	1.46 (1.08–1.96)	0.013	27/103	1.76 (1.15–2.69)	0.009	17/103	1.61 (0.95–2.72)	0.077
> 918 copies/10⁶ globin	62/104	1.85 (1.40–2.46)	< 0.001	64/104	1.85 (1.41–2.44)	< 0.001	34/104	2.37 (1.61–3.51)	< 0.001	18/104	1.70 (1.01–2.87)	0.047
P_trend			< 0.001			< 0.001			< 0.001			0.023

n: the number of events; N: the total number of patients in each group. a: Adjusted for age, gender, smoking status, T stage, N stage, radiotherapy technology, chemotherapy (induced chemotherapy, concurrent chemotherapy, and adjuvant chemotherapy), and education levels. b: Adjusted for age, gender, smoking status, T stage, N stage, radiotherapy technology, and chemotherapy (induced chemotherapy, concurrent chemotherapy, and adjuvant chemotherapy).