Table 4

aOR of breast cancer development associated with having additional one high-risk genotype of estrogen-metabolizing genes, stratified by risk factors of estrogen exposure or BMI

Risk factorCase (%)Control (%)aORa (95% CI)
Total years of estrogen exposureb
 ≥30 yrs85 (61.2)83 (62.4)1.74 (1.05–2.95)
 <30 yrs54 (38.8)50 (37.6)1.65 (0.82–3.51)
Years of estrogen exposure before FFTPc
 ≥10 yrs95 (68.4)61 (45.9)1.70 (1.01–1.03)
 <10 yrs44 (31.6)72 (54.1)1.63 (0.81–3.39)
Age at menarche
 ≤13 yrs57 (41.0)38 (28.6)1.83 (1.00–3.66)
 >13 yrs82 (59.0)95 (71.1)1.58 (0.89–2.87)
BMI (kg/m−2)
 ≥22.566 (47.5)89 (66.9)1.91 (1.07–3.51)
 <22.573 (52.5)44 (33.1)1.42 (0.78–2.68)
  • a aOR of breast cancer development associated with the number of high-risk genotypes (of CYP17, CYP1A1, and COMT) was calculated in a multivariate logistic regression model containing the number of high-risk genotypes (three versus two versus one versus zero), age, and family history of breast cancer.

  • b For premenopausal women, total years of estrogen exposure = age − age at menarche; for postmenopausal women, total years of estrogen exposure = age at menopause − age at menarche.

  • c For postmenopausal nulliparous women, this index = age at menopause − age at menarche; for other women, this index = age at FFTP − age at menarche.