Skip to main content

Table 1 Associations between demographic and lifestyle characteristics and risk of breast cancer, adjusted for age and time of entry into the cohort

From: White blood cell DNA methylation and risk of breast cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO)

  Controls % Cases % Odds Ratio, 95% CI
Age (years)
 <59 150 35.8 151 35.3 1.0 (referent)   
 60–64 140 33.4 141 32.9 1.00 0.72 1.39
 65–69 93 22.2 102 23.8 1.09 0.76 1.56
  > =70 36 8.6 34 7.9 0.94 0.56 1.58
Time of entry
  > =October 10, 1997 168 40.1 174 40.7 1.0 (referent)   
  < =September 30, 1997 251 59.9 254 59.4 1.02 0.78 1.35
Race
 White, non-Hispanic 380 90.7 395 92.3 1.0 (referent)   
 Other 39 9.3 33 7.7 0.81 0.50 1.32
Body mass index (kg/m2)
 Underweight-normal (15–24.99) 175 41.9 176 41.2 1.0 (referent)   
 Overweight (25.0–29.99) 141 33.7 152 35.6 1.07 0.79 1.46
 Obese (> = 30) 102 24.4 99 23.2 0.96 0.68 1.36
Age at menarche (years)
 <12 70 16.8 88 20.6 1.0 (referent)   
 12–13 238 56.9 219 51.2 0.73 0.51 1.05
  > =14 110 26.3 121 28.3 0.87 0.58 1.31
Number of live births
 None 31 7.4 48 11.2 1.0 (referent)   
 1–2 births 123 29.4 147 34.4 0.77 0.46 1.29
 3+ births 265 63.3 233 54.4 0.57 0.35 0.92
Age at first birth (years)
 <20 72 17.2 55 12.9 1.0 (referent)   
 20–24 209 49.9 181 42.5 1.14 0.76 1.70
 25–29 80 19.1 108 25.4 1.77 1.12 2.79
  > =30 27 6.4 34 8.0 1.66 0.89 3.07
 Nulliparous 31 7.4 48 11.3 2.03 1.14 3.59
Type of menopause
 Natural 253 60.4 283 66.1 1.0 (referent)   
 Bilateral oophorectomy 49 11.7 29 6.8 0.52 0.31 0.85
 Other 117 27.9 116 27.1 0.88 0.65 1.20
Age at natural menopause (years)
 <50 91 36.0 95 33.7 1.0 (referent)   
 50–54 122 48.2 141 50.0 1.15 0.79 1.69
 55+ 40 15.8 46 16.3 1.15 0.69 1.93
History of benign breast disease
 No 285 69.9 261 61.9 1.0 (referent)   
 Yes 123 30.2 161 38.2 1.43 1.07 1.91
Smoking status
 Never 257 61.3 229 53.5 1.0 (referent)   
 Former 135 32.2 163 38.1 1.36 1.02 1.82
 Current 27 6.4 36 8.4 1.51 0.89 2.56
Recent alcohol intake
 No 112 29.2 99 24.9 1.0 (referent)   
 Yes 272 70.8 298 75.1 1.25 0.91 1.72
Family history of breast cancer
 No 353 85.9 340 81.0 1.0 (referent)   
 Yes 58 14.1 80 19.1 1.43 0.99 2.07
Hormone user
 Never 111 26.7 102 23.9 1.0 (referent)   
 Former 70 16.8 55 12.9 0.86 0.55 1.34
 Current 235 56.5 269 63.2 1.26 0.91 1.75