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Table 1 Descriptive characteristics of breast cancer and lung cancer cases and referents diagnosed in years 2000–2007 (N = 61,129)

From: A case-referent study: light at night and breast cancer risk in Georgia

Individual-level variables Cases (N = 42,754) Referents (N = 18,375)
  N % N %
LAN mean value (watts per cm 2 per sterradian)*   
  High (> 41) 27,121 71 10,970 60
  Medium (21–41) 5,974 14 2,623 14
  Low (0–20) 9,659 23 4,782 26
Race*  
  White 31,638 75 14,885 82
  Black 10,461 25 3,364 18
Geocoding Match Status*  
  Matched 34,053 80 14,458 79
  Unmatched 8,701 20 3,917 21
Tumor Grade*  
  Grade 1 7,496 18 785 4
  Grade 2 15,117 35 2,411 13
  Grade 3 14,741 34 5,207 29
  Other 5,348 13 9,915 54
Tumor Stage*  
  Distant 1,992 5 8,230 45
  Local 25,732 60 3,665 20
  Regional 13,690 32 4,697 25
  Unstaged 1,340 3 1,783 10
  Mean (SD) Mean (SD)
Mean age at diagnosis 60 (14) 68 (12)
Mean LAN value (watts per cm 2 per sterradian) 35 (292) 18 (491)
County-level variables Cases (N = 34,053) Referents (N = 14,458)
Average family size*   
  ≥ 3.17 25,206 74 10,103 70
  < 3.17 8,847 26 4,328 30
Median household Income* (quartiles)  
  < $27,869 982 3 486 3
  ≥ $27,869 - $31,950 3,227 10 1,546 11
  > $31,950 - $38,799 8,296 24 4,098 28
  > $38,799 21,548 63 8,328 58
MSA Status* (2003)  
  MSA 28,523 84 11,757 81
  Non-MSA 5,530 16 2,701 19
Annual PM 2.5 level* (quartiles)  
  < 11.4 2,076 6 1,016 7
  ≥ 11.4-13.1 3,202 9 1,514 10
  >13.1-15.2 7,016 21 3,282 23
  >15.2 21,759 64 8,646 60
Per 1,000 women aged 15–50, number of births in last year* (quartiles)  
  < 40 2,621 8 1,211 8
  ≥ 40 - 54 7,217 21 3,299 23
  > 54 – 66 18,384 54 7,066 49
  > 66 5,831 17 2,882 20
Total population living in MSA/PMSA, percentage living in different residence in 1995*  
  No change in residence since 1995 8,693 26 4,372 30
  Change in residence since 1995 25,360 74 10,086 70
Percent female smokers, public health district level* (quartiles)  
  < 19.5% 13,113 39 4,783 33
  ≥ 19.5% - 21.4% 9,907 29 4,165 29
  > 21.4% - 22.3% 2,814 8 1,271 9
  > 22.3% 8,219 24 4,239 29
  Mean (SD) Mean (SD)
Percentage of population below the poverty line 14.43 (5.64) 14.79 (5.57)
Percentage of African-American females 29.60 (17.92) 28.29 (17.92)
Percent high school graduate or higher 84.00 (6.11) 83.05 (6.38)
Percentage of population over 16 in labor force 66.58 (5.64) 65.79 (5.72)
Percentage of population in different residence in 1995 48.07 (5.29) 47.35 (5.46)
  1. Abbreviations: LAN, Light at night in watts per cm2 per sterradian; SD, Standard Deviation; MSA, Metropolitan Statistical Area; PM, Particulate Matter2.5.
  2. Case: (breast cancer); Referent (lung cancer).
  3. Match Status: Only cancer cases registering address level accuracy (AI0-AX3) were included for analysis.
  4. Annual PM 2.5 level; annual average ambient concentrations of PM 2.5 in micrograms per cubic meter, based on seasonal averages and daily measurement, 2001.
  5. * Statistically significant chi-square result (p < 0.05).
  6. Number of cases and referents differ from individual-level analysis figures; some responses regarding county location were missing and dropped from analysis.