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Table 1 Study characteristics of breast cancer cases nested within the Multiethnic Cohort (MEC)

From: Urinary phthalate exposures and risk of breast cancer: the Multiethnic Cohort study

  All cases Controls
N = 1032 % N = 1030 %
Area
 Hawaii 883 85.6 881 85.5
 Los Angeles 149 14.4 149 14.5
Urine typea
 First morning 157 15.2 157 15.2
 Overnight 875 84.8 873 84.8
Mean age at urine collection, yrs ± SD 66.7 ± 7.7   66.8 ±7.7  
 ≤ 64 487 47.2 470 45.6
 65–74 376 36.4 387 37.6
 75+ 169 16.4 173 16.8
Race/ethnicity
 Japanese American 478 46.3 478 46.4
 White 274 26.6 273 26.5
 African American (AA) 48 4.7 49 4.8
 Latino 77 7.5 76 7.4
 Native Hawaiian (NH) 155 15.0 154 15.0
Education
 ≤ High school 420 40.7 424 41.2
 Some college 216 20.9 217 21.1
 College graduate 192 18.6 202 19.6
 Graduate school 199 19.3 180 17.5
 Missing 5 0.5 7 0.7
Age at menarche, yrs
 < 12 555 53.8 570 55.3
 13–14 370 35.9 359 34.9
 > 14 100 9.7 95 9.2
 Missing 7 0.7 6 0.6
Number of children
 Nulliparous 163 15.8 111 10.8
 1 child 98 9.5 116 11.3
 2–3 children 523 50.7 553 53.7
 > 4 children 245 23.7 245 23.8
 Missing 3 0.3 5 0.5
Age at first live birth, yrs
 Nulliparous 163 15.8 111 10.8
 15–20 211 20.4 208 20.2
 21–30 564 54.7 614 59.6
 > 30 82 7.9 76 7.4
 Missing 12 1.2 21 2.0
Menopausal status
 Premenopause 213 20.6 208 20.2
 Natural menopause 509 49.3 505 49.0
 Other surgery 120 11.6 134 13.0
 Surgical menopause 160 15.5 154 15.0
 Other or missing reasons 30 2.9 29 2.8
Use of hormone therapy at urine collection
 Never estrogen (E]) 400 38.8 409 39.7
 Past E 337 32.7 350 34.0
 Current E alone 186 18.0 184 17.9
 Current E + progesterone 100 9.7 78 7.6
 Missing 9 0.9 9 0.9
Neighborhood SES at urine collection
 Quintile 1–low 100 9.7 123 11.9
 Quintile 2 147 14.2 153 14.9
 Quintile 3 154 14.9 162 15.7
 Quintile 4 233 22.6 220 21.4
 Quintile 5–high 345 33.4 316 30.7
 Missing 53 5.1 56 5.4
BMI at urine collection (kg/m2)
 Mean BMI ± SD 27.1 ± 5.6   26.0 ± 5.6  
 < 25 406 39.3 529 51.4
 ≥ 25- < 30 366 35.5 316 30.7
 ≥ 30 260 25.2 185 18.0
Waist-hip ratio (WHR)d
 Mean ± SD 0.862 ± 0.076   0.858 ± 0.082  
 < 0.854 384 37.2 475 46.1
 ≥ 0.854 457 44.3 471 45.7
Missing 191 18.5 84 8.2
Waist (inches)d
 Mean ± SD 35.51 ± 5.51   34.72 ± 5.47  
 < 34 331 32.1 425 41.3
 ≥ 34 513 49.7 524 50.9
Missing 188 18.2 81 7.9
Smoking status
 Never 578 56.0 618 60.0
 Former 315 30.5 300 29.1
 Current 133 12.9 104 10.1
 Missing 6 0.6 8 0.8
Mediterranean diet scoree
 Quartile 1–low 350 33.9 350 34.0
 Quartile 2 207 20.1 204 19.8
 Quartile 3 220 21.3 204 19.8
 Quartile 4–high 232 22.5 252 24.5
 Missing 23 2.2 20 1.9
Stageb
 In situ 224 21.7   
 I (1) 613 59.4   
 II (2) 10 1.0   
 III (3,4,7) 175 17.0   
 Missing 10 1.0   
Hormone receptor (HR) statusc
 Estrogen (ER) + or progesterone (PR) 859 83.2   
 ER− and PR− 124 12   
 Missing 49 4.7   
  1. aAll urines from Los Angeles were first morning samples. All urines from Hawaii were overnight (99%) or first morning urines (1%)
  2. bOf the 10 missing stage, 2 were ER+ or PR+, 2 were ER− and PR−, and 6 were missing stage
  3. cOf the 49 missing HR status, there were 35 in situ, 6 stage I, 1 stage II, 1 stage III, and 6 missing stage
  4. dWaist-hip ratio (WHR) information was collected at the third follow-up questionnaire (2003–2006); we included subjects with WHR information before breast cancer diagnosis and for all control women
  5. eThe Mediterranean diet included 9 components (vegetables, fruit, nuts, legumes, whole grains, fish, alcohol, monounsaturated: saturated fat ratio, and red/processed meat) (Ref [26], Harmon et al.)