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Table 2 Selected characteristics of participants

From: Body mass index and lung cancer risk: a pooled analysis based on nested case-control studies from four cohort studies

Characteristic Cases (n = 4172)
N (%)
Controls (n = 8471)
N (%)
P value (X2)
Sex 0.37
 Men 3043 (72.9) 6135 (72.4)  
 Women 1129 (27.1) 2336 (27.6)  
Age <.0001
  < 45 76 (1.8) 197 (2.3)  
 45–49 211 (5.1) 980 (11.6)  
 50–54 602 (14.4) 1720 (20.3)  
 55–59 1010 (24.2) 2165 (25.5)  
 60–64 1216 (29.2) 2024 (23.9)  
 65–69 731 (17.5) 1070 (12.6)  
  ≥ 70 326 (7.8) 324 (3.8)  
BMI (kg/m2) a <.0001
 Underweight 250 (5.9) 408 (4.8)  
 Normal weight 2150 (51.5) 4276 (50.5)  
 Overweight 112 (26.7) 2746 (32.4)  
 Obese 373 (8.9) 934 (11.0)  
 Missing 287 (6.9) 107 (1.3)  
Education <.0001
 None 529 (12.7) 699 (8.3)  
 Primary 1515 (36.3) 2518 (29.7)  
 Middle/Vocational 851 (20.4) 2109 (24.9)  
 Secondary 457 (11.0) 1060 (12.5)  
 Postsecondary/Technical 312 (7.5) 665 (7.9)  
 University 381 (9.1) 1164 (13.7)  
 Unknown/not specified 26 (0.6) 51 (0.6)  
 Missing 101 (2.4) 205 (2.4)  
Smoking status <.0001
 Never 571 (13.7) 3144 (37.1)  
 Former 694 (16.6) 1735 (20.5)  
 Current 2892 (69.3) 3556 (42.0)  
 Missing b 15 (0.36) 36 (0.4)  
Pack-years of smoking <.0001
 0 571 (13.7) 3144 (37.1)  
  < 20 547 (13.1) 1562 (18.4)  
 20–29 554 (13.3) 850 (10.0)  
 30–39 691 (16.6) 891 (10.5)  
 40–49 817 (19.6) 829 (9.8)  
  ≥ 50 831 (19.9) 892 (10.5)  
 Missing 161 (3.9) 303 (3.6)  
Age at diagnosis of lung cancer, y
 Mean (SD) 68.0 (8.1)  
 Median (range) 68.2 (38.1–91.0)   
Time elapsed, y
 Mean (SD) 8.3 (5.4) c 13.3 (5.1) d  
 Median (range) 7.3 (0–27) 13.0 (0–28)  
Histological Type
 Adenocarcinoma 1182 (42.6)   
 Squamous cell carcinoma 897 (32.6)   
 Large cell carcinoma 221 (7.9)   
 Small cell carcinoma 473 (17.1)   
  1. aUnderweight (BMI < 18.5), normal weight (18.5 ≤ BMI < 25), overweight (25 ≤ BMI < 30) and obese (BMI ≥ 30)
  2. bSubjects who had missing cigarettes smoked per day and duration of smoking
  3. cPeriod between enrollment and diagnosis
  4. dPeriod between enrollment and last follow-up/observation