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. 2003 Oct 28;89(9):1661–1663. doi: 10.1038/sj.bjc.6601293

Table 1. Risk of breast cancer defined by ER/PR subtype in Australian women under the age of 40 years according to risk factor.

  ER+PR+
ER+PR−
ER−PR+
ER−PR−
ER? &/or PR?
Control  
  N=323 OR (95% CI)c N=34 OR (95% CI) N=80 OR (95% CI) N=181 OR (95% CI) N=147 OR (95% CI) N=564 LRTb
1° relative with breast cancer
 Yes 9%   12%   8%   11%   9%   4%  
 Yes (ref: No)   2.5 (1.4–4.6)   3.4 (1.1–11)   1.8 (0.6–4.8)   3.4 (1.8–6.4)   2.2 (1.1–4.5)   P=0.8
 
Height
 ⩾163 59%   62%   70%   59%   58%   55% P=0.3
 ⩾163 (ref: <163)   1.2 (0.9–1.6)   1.3 (0.6–2.7)   1.8 (1.0–3.1)   1.3 (0.9–1.8)   1.4 (0.9–2.1)    
 
Body mass index
 ⩾23 43%   50%   46%   50%   51%   46% P=0.5
 ⩾23 (ref: <23)   0.9 (0.7–1.2)   1.2 (0.6–2.3)   1.0 (0.6–1.6)   1.1 (0.8–1.5)   1.3 (0.9–1.3)    
 
Age at menarche
 ⩾13 years 60%   65%   62%   53%   60%   63%  
 ⩾13 years (ref: <13)   0.8 (0.6–1.1)   0.9 (0.5–1.8)   0.8 (0.5–1.3)   0.6 (0.4–0.9)   0.9 (0.6–1.3)   P=0.5
                         
Ever use of oral contraceptives
 Yes 93%   91%   96%   92%   91%   91%  
 Yes (ref: No)   1.1 (0.7–1.9)   1.3 (0.4–4.0)   1.1 (0.5–2.5)   0.9 (0.5–1.6)   1.0 (0.6–1.9)   P=0.6
 
Ever had live birth
 Yes 69%   74%   73%   72%   73%   65%  
 Yes (ref: No)   1.0 (0.7–1.4)   1.7 (0.7–4.4)   1.4 (0.8–2.6)   1.0 (0.7–1.6)   1.0 (0.6–1.7)   P=0.9
 
Age at first live birthd
 ⩾25 67%   64%   69%   56%   56%   59%  
 ⩾25 (ref: <25)   1.7 (1.1–2.5)   1.7 (0.7–4.3)   1.3 (0.7–2.5)   0.9 (0.6–1.4)   1.0 (0.6–1.7)   P=0.2
 
Number of live births
 1 13%   24%   28%   17%   14%   12%  
 1 (ref: 0)   1.1 (0.7–1.7)   2.6 (0.9–7.1)   2.6 (1.3–5.2)   1.3 (0.8–2.3)   1.1 (0.6–2.1)    
 2 35%   26%   28%   36%   38%   29%  
 2 (ref: 0)   1.0 (0.7–1.5)   1.3 (0.5–3.8)   1.0 (0.5–2.0)   1.0 (0.6–1.7)   1.1 (0.7–1.9)    
 ⩾3 21%   24%   18%   19%   21%   24% P=0.8
 ⩾3 (ref: 0)   1.0 (0.5–1.2)   1.4 (0.5–4.3)   0.9 (0.4–1.9)   0.8 (0.4–1.3)   0.8 (0.4–1.4)    
a

aPolytomous logistic regression adjusted for study centre, study period, reference age, highest completed education level, country of birth, marital status, affected first-degree relative, height, body mass index, age at menarche, number of live births, and ever used oral contraceptives.

b

Likelihood ratio test.

c

Odds ratio with 95% confidence interval.

d

Parous women only.