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. 2015 May 13;4(9):1432–1439. doi: 10.1002/cam4.456

Table 1.

Risk factor distributions

Risk factor Controls (n = 2990) Cases (n = 551)
Age (range) 47 (20,55) 47 (24,55)
White race (%) 87% 93%
Premenopausal BMI, median (range) 23 (16,55) 23 (16,44)
Postmenopausal BMI, median (range) 24 (16,62) 24 (17,35)
Family history of breast cancer 7% 13%
Prior benign breast disease 12% 18%
Age at menarche, median (range) 13 (8,20) 12 (8,18)
Nulliparity 14% 15%
Number of children, median (range) 3 (1,13) 3 (1,9)
Age at first birth, median (range) 23 (11,43) 23 (13,40)
Months of breastfeeding, median (range) 1 (0,168) 1 (0.98)
Postmenopausal 40% 37%
Age at menopause, median (range) 42 (21.53) 42 (23,53)
Estrogen receptor positive by IHC1 NA 57%
Progesterone receptor positive by IHC1 NA 51%
ERBB2 (HER2) positive by IHC1 NA 21%

BMI, body mass index; IHC, immunohistochemistry; ERBB2, human epidermal growth factor receptor.

1

33 cases are missing immunohistochemistry data.