Table 1.
Characteristics of nasopharyngeal carcinoma affected individuals and control subjects among the original, replication, and pooled studies
| Variables | Original study |
Replication study |
Pooled study |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Affected individuals n = 572 n (%) | Control subjects n = 696 n (%) | p | Affected individuals n = 497 n (%) | Control subjects n = 826 n (%) | p | Affected individuals n = 1,069 n (%) | Control subjects n = 1,522n (%) | p | |
| Age, years | – | – | 0.103 | – | – | 0.002 | – | – | 2.2E−4 |
| Mean (SD) | 48.6 (10.9) | 49.6 (10.7) | 0.108 | 49.2 (10.8) | 51.1 (10.9) | 0.003 | 48.9 (10.8) | 50.4 (10.8) | 3.9E−4 |
| <35 | 58 (10.1) | 52 (7.5) | – | 45 (9.1) | 53 (6.4) | – | 103 (9.6) | 105 (6.9) | – |
| 35–59 | 424 (74.1) | 512 (73.6) | – | 366 (73.6) | 568 (68.8) | – | 790 (73.9) | 1,080 (71.0) | – |
| >59 | 90 (15.7) | 132 (19.0) | – | 86 (17.3) | 205 (24.8) | – | 176 (16.5) | 337 (22.1) | – |
| Sex | – | – | 0.879 | – | – | 0.928 | – | – | 0.819 |
| Male | 431 (75.4) | 527 (75.7) | – | 381 (76.7) | 635 (76.9) | – | 812 (76.0) | 1,162 (76.4) | – |
| Female | 141 (24.7) | 169 (24.3) | – | 116 (23.3) | 191 (23.1) | – | 257 (24.0) | 360 (23.7) | – |
| Education level, years | – | – | 0.117 | – | – | 0.102 | – | – | 0.021 |
| <7 | 229 (40.0) | 247 (35.5) | – | 216 (43.5) | 310 (37.5) | – | 445 (41.6) | 557 (36.6) | – |
| 7–9 | 233 (40.7) | 286 (41.1) | – | 179 (36.0) | 327 (39.6) | – | 412 (38.5) | 613 (40.3) | – |
| ≥10 | 110 (19.2) | 163 (23.4) | – | 102 (20.5) | 189 (22.9) | – | 212 (19.8) | 352 (23.1) | – |
| Residential area | – | – | 4.6E−6 | – | – | 0.251 | – | – | 2.9E−5 |
| Urban | 96 (16.8) | 58 (8.3) | – | 65 (13.1) | 89 (10.8) | – | 161 (13.1) | 147 (10.8) | – |
| Rural | 476 (83.2) | 638 (91.7) | – | 432 (86.9) | 737 (89.2) | – | 908 (86.9) | 1,375 (89.2) | – |
| Salt-preserved fish consumption in 2000–2002 | – | – | 0.186 | – | – | 0.027 | – | – | 0.119 |
| Yearly or less | 390 (68.2) | 450 (64.7) | – | 431 (86.7) | 678 (82.1) | – | 821 (76.8) | 1,128 (74.1) | – |
| Monthly or more | 182 (31.8) | 246 (35.3) | – | 66 (13.3) | 148 (17.9) | – | 248 (23.2) | 394 (25.9) | – |
| NPC history among first-degree relatives | – | – | 1.9E−8 | – | – | 7.3E−5 | – | – | 2.4E−13 |
| No | 487 (85.1) | 653 (93.8) | – | 449 (90.3) | 790 (95.6) | – | 936 (87.6) | 1,443 (94.8) | – |
| Yes | 73 (12.8) | 26 (3.7) | – | 39 (7.9) | 22 (2.7) | – | 112 (10.5) | 48 (3.2) | – |
| Unknown/missing | 12 (2.1) | 17 (2.4) | – | 9 (1.8) | 14 (1.7) | – | 21 (2.0) | 31 (2.0) | – |
| Smoking status | – | – | 0.732 | – | – | 0.785 | – | – | 0.864 |
| Never | 224 (39.2) | 266 (38.2) | – | 217 (43.7) | 367 (44.4) | – | 441 (41.3) | 633 (41.6) | – |
| Ever | 348 (60.8) | 430 (61.8) | – | 280 (56.3) | 459 (55.6) | – | 628 (58.8) | 889 (58.4) | – |
| Current occupation | – | – | 3.9E−12 | – | – | 5.5E−4 | – | – | 1.0E−5 |
| Farmer/Unemployment | 208 (36.4) | 232 (33.3) | – | 192 (38.6) | 388 (47.0) | – | 400 (37.4) | 620 (40.7) | – |
| Blue collar | 236 (41.3) | 213 (30.6) | – | 190 (38.2) | 265 (32.1) | – | 426 (39.9) | 478 (31.4) | – |
| White collar | 89 (15.6) | 102 (14.7) | – | 59 (11.9) | 118 (14.3) | – | 148 (13.8) | 220 (14.5) | – |
| Unknown | 39 (6.8) | 149 (21.4) | – | 56 (11.3) | 55 (6.7) | – | 95 (8.9) | 204 (13.4) | – |
| Selected environmental exposurea | – | – | 6.5E−19 | – | – | 0.029 | – | – | 1.3E−16 |
| None | 58 (10.1) | 82 (11.8) | – | 35 (7.0) | 85 (10.3) | – | 93 (8.7) | 167 (11.0) | – |
| Dust exposure | 226 (39.5) | 217 (31.2) | – | 246 (49.5) | 326 (39.5) | – | 472 (44.2) | 543 (35.7) | – |
| Smoke/exhaust exposure | 107 (18.7) | 91 (13.1) | – | 125 (25.2) | 167 (20.2) | – | 232 (21.7) | 258 (17.0) | – |
| Other exposure | 175 (30.6) | 193 (27.7) | – | 85 (17.1) | 245 (29.7) | – | 260 (24.3) | 438 (28.8) | – |
| Unknown/missing | 6 (1.1) | 113 (16.2) | – | 6 (1.2) | 3 (0.4) | – | 12 (1.1) | 116 (7.6) | – |
| EBV infection determined by variant 163364 | – | – | 0.693 | – | – | 0.692 | – | – | 0.890 |
| Multiple strains | 16 (2.8) | 17 (2.4) | – | 16 (3.2) | 30 (3.6) | – | 32 (3.0) | 47 (3.1) | – |
| Single strain | 556 (97.2) | 679 (97.6) | – | 481 (96.8) | 796 (96.4) | – | 1,037 (97.0) | 1475 (96.9) | – |
Multiple strains represent the genotype CT for EBV variant 163364; single strain represents the genotype C or T for the same variant.
a
Dust exposure includes exposure to wood, metal, textile, leather, cement, and other types of non-soil dust. Smoke/exhaust exposure includes exposure to exhaust of diesel, gasoline, coal, firewood, asphalt/tar, nature gas, and other types of exhaust/smoke. Other environmental exposure includes exposure to wood preservatives, formaldehyde, organic solvents, pesticides, and other types of chemical vapor, as well as sulfuric acid, hydrochloride, and other types of acid/alkali.