Table 2. Distribution of study characteristics among lung cancer cases and cancer-free controls.
| Variables | Cases (N=399) |
Controls (N=466) |
Pa |
|---|---|---|---|
| N (%) | N (%) | ||
| Age (years) | |||
| ≤ 44 | 59 (14.8) | 83 (17.8) | 0.07 |
| 45 - 54 | 96 (24.1) | 139 (29.8) | |
| 55 - 64 | 111 (27.8) | 116 (24.9) | |
| ≥ 65 | 133 (33.3) | 128 (27.5) | |
| Mean (SD) | 58.1 (11.9) | 56.1 (11.3) | 0.01 |
| Sex | |||
| Male | 202 (50.6) | 234 (50.2) | 0.90 |
| Female | 197 (49.4) | 232 (49.8) | |
| Education | |||
| Illiteracy | 43 (10.8) | 23 (4.9) | < 0.0001 |
| Primary School | 106 (26.6) | 81 (17.4) | |
| Middle School | 124 (31.1) | 175 (37.5) | |
| High School | 68 (17.0) | 120 (25.8) | |
| College and above | 58 (14.5) | 67 (14.4) | |
| Average annual income/person 10 years ago (RMB)b | |||
| < 1000 | 104 (26.1) | 106 (22.7) | < 0.0001 |
| 1000 – 2499 | 236 (59.1) | 197 (42.3) | |
| 2500 – 4999 | 37 (9.3) | 116 (24.9) | |
| ≥ 5000 | 22 (5.5) | 47 (10.1) | |
| Mean (SD) | 1994.5 (2678.9) | 2539.4 (3193.7) | 0.007 |
| BMI (Kg/m2) | |||
| < 18.5 | 22 (5.8) | 9 (2.0) | < 0.0001 |
| 18.5 – 24.9 | 250 (66.3) | 259 (56.3) | |
| 25 – 29.9 | 90 (23.9) | 162 (35.2) | |
| ≥ 30 | 15 (4.0) | 30 (6.5) | |
| Mean (SD) | 23.4 (3.6) | 24.8 (3.9) | <0.0001 |
| Pack years of smoking | |||
| Never smokersc | 179 (44.9) | 285 (61.2) | <0.0001 |
| < 30 | 64 (16.0) | 107 (22.9) | |
| ≥ 30 | 156 (39.1) | 74 (15.9) | |
| Indoor air pollutiond | |||
| None | 38 (10.8) | 90 (19.7) | <0.0001 |
| Low | 145 (41.2) | 253 (55.2) | |
| High | 169 (48.0) | 115 (25.1) | |
| Alcohol drinkinge | |||
| Never | 298 (74.7) | 345 (74.0) | 0.83 |
| Ever | 101 (25.3) | 121 (26.0) | |
| Tea drinking | |||
| Never | 242 (60.7) | 263 (56.4) | 0.21 |
| Ever | 157 (39.3) | 203 (43.6) | |
| Supplement usef | |||
| No | 342 (87.0) | 355 (77.2) | 0.0002 |
| Yes | 51 (13.0) | 105 (22.8) |
a
from two sided χ2 test for categorical variables and from t test for continuous variables. p-values in bold represent statistical significance;
b
RMB = Renminbi, the Chinese currency;
c
smoked less than 100 cigarettes during lifetime;
d
Indoor air pollution exposure was calculated by summarizing participant's exposure to solid fuel for cooking and heating, ventilation in kitchen, opening of windows in winter and second hand smoking (an index of 0 = none, 1-2 = low and 3-5 = high indoor air pollution).
e
lifetime alcohol drinking status.
f
supplement use includes intake of one or more of the following: vitamin A, beta-carotene, vitamin C, vitamin E, calcium, selenium, zinc or multivitamins.