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 (%)] | ||||
|---|---|---|---|---|---|---|
| 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) | 0.001a | 15 (7.9) | 47 (61.8) | < 0.001b |
| Locoregional | 4 (4.0) | 4 (23.5) | 0.015a | 13 (6.8) | 18 (23.7) | < 0.001b |
| Distant with or without locoregional | 0 (0) | 2 (11.8) | 0.020a | 2 (1.0) | 29 (38.2) | < 0.001b |
a P values were calculated using Fisher’s exact test when any number was < 5
b P values were calculated using the χ² test