Characteristic | Case–control study [cases (%)] | Nested case–control study [cases (%)] | ||||
---|---|---|---|---|---|---|
NPC patients | Controls | P value | NPC patients | Controls | P value | |
Total | 150 | 150 | 60 | 120 | ||
Gender | 1.000 | 1.000 | ||||
Male | 130 (86.7) | 130 (86.7) | 35 (58.3) | 70 (58.3) | ||
Female | 20 (13.3) | 20 (13.3) | 25 (41.7) | 50 (41.7) | ||
WHO histological classification | ||||||
I | 5 (3.3) | NA | 2 (3.3) | NA | ||
II | 3 (2.0) | NA | 1 (1.7) | NA | ||
III | 142 (94.7) | NA | 57 (95.0) | NA | ||
Clinical stage | ||||||
Early (I + II) | 51 (34.0) | NA | 35 (60.3) | NA | ||
Advanced (III + IV) | 99 (66.0) | NA | 23 (39.7) | NA | ||
Unknown | 0 | NA | 2 | NA | ||
EBNA1/IgA | ||||||
Seronegative | 52 (34.7) | 120 (80.0) | < 0.001 | 28 (46.7) | 115 (95.8) | < 0.001 |
Seropositive | 98 (65.3) | 30 (20.0) | 32 (53.3) | 5 (4.2) |