Prognostic value of plasma Epstein–Barr virus DNA level during posttreatment follow-up in the patients with nasopharyngeal carcinoma having undergone intensity-modulated radiotherapy

Table 2 Association between the status of plasma Epstein–Barr virus (EBV) DNA during posttreatment follow-up and tumor recurrence in the 385 patients with NPC who were treated with IMRT and stratified by the status of pretreatment plasma EBV DNA

Site of first recurrence	Undetectable pretreatment plasma EBV DNA [n (%)]			Detectable pretreatment plasma EBV DNA [n (%)]
Site of first recurrence	Undetectable plasma EBV DNA during posttreatment follow-up (n = 101)	Detectable plasma EBV DNA during posttreatment follow-up (n = 17)	P	Undetectable plasma EBV DNA during posttreatment follow-up (n = 191)	Detectable plasma EBV DNA during posttreatment follow-up (n = 76)	P
Any recurrence	4 (4.0)	6 (35.3)	0.001^a	15 (7.9)	47 (61.8)	< 0.001^b
Locoregional	4 (4.0)	4 (23.5)	0.015^a	13 (6.8)	18 (23.7)	< 0.001^b
Distant with or without locoregional	0 (0)	2 (11.8)	0.020^a	2 (1.0)	29 (38.2)	< 0.001^b

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