Table 2 Characteristics of the study participants at baseline, by breast cancer status
From: Association of air pollution with postmenopausal breast cancer risk in UK Biobank
Characteristic | Women who developed breast cancer (N = 6146) | Women without breast cancer (N = 149,089) |
|---|---|---|
Mean (SD) | ||
Age at enrollment, yearsa | 60.59 (5.10) | 60.06 (5.54) |
Follow-up time, yearsa | 5.35 (3.14) | 10.73 (2.00) |
Age at menarche, yearsb | 12.93 (1.61) | 12.96 (1.59) |
Age at menopause, yearsa | 50.34 (4.92) | 49.72 (5.09) |
BMI, kg/m2a | 27.61 (5.01) | 27.15 (5.07) |
NO2 2005 | 29.53 (9.97) | 29.57 (9.93) |
NO2 2006 | 28.58 (9.09) | 28.64 (9.03) |
NO2 2007 | 30.36 (10.56) | 30.37 (10.53) |
NO2 2010 | 26.30 (7.51) | 26.41 (7.45) |
PM10 2007b | 22.09 (2.78) | 22.00 (2.86) |
PM10 2010 | 16.21 (1.90) | 16.20 (1.89) |
PM2.5 2010 | 9.94 (1.04) | 9.95 (1.04) |
PM2.5 absorbance 2010 | 1.18 (0.26) | 1.18 (0.27) |
PM coarse 2.5–10 2010 | 6.43 (0.91) | 6.42 (0.89) |
NOx 2010 | 43.32 (15.22) | 43.52 (15.15) |
N (%) | ||
 Raceb |  |  |
  White | 5928 (96.45) | 142,539 (95.61) |
  Other | 218 (3.55) | 6550 (4.39) |
 Parity/AFB, yearsb |  |  |
  Nulliparous | 1049 (17.07) | 24,209 (16.24) |
  Any children with age at first birth ≤ 25 years | 2341 (38.09) | 59,787 (40.10) |
  Any children with age at first birth > 25 years | 1904 (30.98) | 46,280 (31.04) |
  Any children with unknown age at first birth | 852 (13.86) | 18,813 (12.62) |
 Postmenopausal hormone-replacement therapya |  |  |
  Never used hormones | 2928 (50.12) | 74,616 (52.63) |
  Past | 2200 (37.66) | 53,915 (38.03) |
  Current | 714 (12.22) | 13,239 (9.34) |
 Family historya |  |  |
  Breast cancer | 682 (11.40) | 10,776 (7.43) |
  No breast cancer | 5301 (88.60) | 134,249 (92.57) |
 Smoking statusb |  |  |
  Never | 3490 (56.78) | 87,433 (58.65) |
  Past | 2131 (34.67) | 49,732 (33.36) |
  Current | 525 (8.54) | 11,924 (8.00) |
 Alcohol intake |  |  |
  Non-drinker | 350 (5.69) | 9145 (6.13) |
  Past drinker | 213 (3.47) | 5622 (3.77) |
  Current drinker | 5583 (90.84) | 134,322 (90.10) |