Table 1.
Characteristics of nasopharyngeal carcinoma cases and controls.
| Characteristics | Cases (No=2499)
|
Controls (No=2576)
|
P value |
|---|---|---|---|
| No (%) | No (%) | ||
| Residential area | 0.39 | ||
| Zhaoqing | 1271 (50.9) | 1303 (50.6) | |
| Wuzhou | 674 (27.0) | 664 (25.8) | |
| Guiping/Pingnan | 554 (22.2) | 609 (23.6) | |
| Sex | 0.96 | ||
| Male | 1835 (73.4) | 1893 (73.5) | |
| Female | 664 (26.6) | 683 (26.5) | |
| Age at diagnosis/referral (years) | |||
| Mean (SD) | 48.5 (10.6) | 49.7 (18.9) | <0.001 |
| 20–29 | 86 (3.4) | 80 (3.1) | 0.004 |
| 30–39 | 417 (16.7) | 371 (14.4) | |
| 40–49 | 904 (36.2) | 880 (34.2) | |
| 50–59 | 677 (27.1) | 724 (28.1) | |
| 60–74 | 415 (16.6) | 521 (20.2) | |
| Education level (years) | 0.003 | ||
| ≤ 6 | 988 (39.5) | 922 (35.8) | |
| 7–9 | 1004 (40.2) | 1030 (40.0) | |
| 10–12 | 401 (16.1) | 483 (18.7) | |
| > 12 | 106 (4.2) | 141 (5.5) | |
| Current housing type | <0.001 | ||
| Building (concrete structure) | 1801 (72.1) | 2007 (77.9) | |
| Cottage (clay brick structure) | 688 (27.5) | 566 (22.0) | |
| Boat | 10 (0.4) | 2 (0.1) | |
| Missing | 0 | 1 (0.04) | |
| Current occupation | <0.001 | ||
| Unemployed | 78 (3.1) | 95 (3.7) | |
| Farmer | 841 (33.7) | 975 (37.9) | |
| Blue-collar | 1016 (40.7) | 895 (34.7) | |
| White-collar | 346 (13.8) | 415 (16.1) | |
| Other/unknown | 218 (8.7) | 196 (7.6) | |
| Cigarette smoking | 0.08 | ||
| Never | 1109 (44.4) | 1206 (46.8) | |
| Ever | 1390 (55.6) | 1368 (53.1) | |
| Missing | 0 | 2 (0.08) | |
| Tea drinking | <0.001 | ||
| Less than daily | 1598 (64.0) | 1502 (58.3) | |
| Daily | 898 (35.9) | 1071 (41.6) | |
| Missing | 3 (0.1) | 3 (0.1) | |
| Salt-preserved fish consumption in 2000–2002 | 0.02 | ||
| Yearly or less | 1835 (73.4) | 1890 (73.4) | |
| Monthly | 476 (19.1) | 534 (20.7) | |
| Weekly or more | 186 (7.4) | 148 (5.7) | |
| Missing | 2 (0.1) | 4 (0.2) |
SD = standard deviation.
*
P value was determined by a two-sided t-test. Other P values were determined by a chi-square test.