Table 2.

Distribution of study characteristics among lung cancer cases and cancer-free controls

Cases (N = 399)Controls (N = 466)
VariablesN (%)N (%)Pa
Age (years)
 ≤4459 (14.8)83 (17.8)0.07
 45–5496 (24.1)139 (29.8)
 55–64111 (27.8)116 (24.9)
 ≥65133 (33.3)128 (27.5)
 Mean (SD)58.1 (11.9)56.1 (11.3)0.01
Sex
 Male202 (50.6)234 (50.2)0.90
 Female197 (49.4)232 (49.8)
Education
 Illiteracy43 (10.8)23 (4.9)<0.0001
 Primary school106 (26.6)81 (17.4)
 Middle school124 (31.1)175 (37.5)
 High school68 (17.0)120 (25.8)
 College and above58 (14.5)67 (14.4)
Average annual income/person 10 years ago (RMB)b
 <1,000104 (26.1)106 (22.7)<0.0001
 1,000–2,499236 (59.1)197 (42.3)
 2,500–4,99937 (9.3)116 (24.9)
 ≥5,00022 (5.5)47 (10.1)
 Mean (SD)1,994.5 (2,678.9)2,539.4 (3,193.7)0.007
BMI (kg/m2)
 <18.522 (5.8)9 (2.0)<0.0001
 18.5–24.9250 (66.3)259 (56.3)
 25–29.990 (23.9)162 (35.2)
 ≥3015 (4.0)30 (6.5)
 Mean (SD)23.4 (3.6)24.8 (3.9)<0.0001
Pack-years of smoking
 Never-smokersc179 (44.9)285 (61.2)<0.0001
 <3064 (16.0)107 (22.9)
 ≥30156 (39.1)74 (15.9)
IAPd
 None38 (10.8)90 (19.7)<0.0001
 Low145 (41.2)253 (55.2)
 High169 (48.0)115 (25.1)
Alcohol drinkinge
 Never298 (74.7)345 (74.0)0.83
 Ever101 (25.3)121 (26.0)
Tea drinking
 Never242 (60.7)263 (56.4)0.21
 Ever157 (39.3)203 (43.6)
Supplement usef
 No342 (87.0)355 (77.2)0.0002
 Yes51 (13.0)105 (22.8)
  • aFrom two-sided χ2 test for categorical variables and from t test for continuous variables. P values in bold represent statistical significance.

  • bRMB, Renminbi, the Chinese currency.

  • cSmoked less than 100 cigarettes during lifetime.

  • dIAP exposure was calculated by summarizing participant's exposure to solid fuel for cooking and heating, ventilation in kitchen, opening of windows in winter, and secondhand smoking (an index of 0 = none, 1–2 = low, and 3–5 = high IAP).

  • eLifetime alcohol drinking status.

  • fSupplement use includes intake of one or more of the following: vitamin A, β-carotene, vitamin C, vitamin E, calcium, selenium, zinc, or multivitamins.