Skip to main content

Table 1 Characteristics of breast cancer case participants and control participants

From: Reproductive factors and the risk of triple-negative breast cancer in white women and African-American women: a pooled analysis

 

Overall

By study

Women’s CARE

Women’s BCIS

Women’s LIFE

Case participants

N = 2658

N = 1197

N = 342

N = 1119

Mean age at diagnosis, years (SD, range)

46.7 (8.1, 22-64)

49.0 (8.6, 35-64)

51.8 (7.3, 35-64)

42.7 (5.4, 22-49)

Race

 White

1960 (73.7%)

678 (56.6%)

287 (83.9%)

995 (88.9%)

 African-American

698 (26.3%)

519 (43.4%)

55 (16.1%)

124 (11.1%)

Subtype of breast cancer

 Triple-negative

554 (20.8%)

335 (28.0%)

21 (6.1%)

198 (17.7%)

 Luminal A-like

1517 (57.1%)

645 (53.9%)

233 (68.1%)

639 (57.1%)

 Luminal B-like

360 (13.5%)

121 (10.1%)

49 (14.3%)

190 (17.0%)

 HER2-enriched

227 (8.5%)

96 (8.0%)

39 (11.4%)

92 (8.2%)

Control participants

N = 2448

N = 2011a

N = 437

Mean age at reference date, years (SD, range)

47.8 (8.3, 24-64)

48.9 (8.4, 35-64)

42.6 (4.9, 24-49)

Race

 White

1549 (63.3%)

1147 (57.0%)

402 (92.0%)

 African-American

899 (36.7%)

864 (43.0%)

35 (8.0%)

Mean age at menarche, years (SD)

12.4 (1.6)

12.4 (1.6)

12.7 (1.5)

Ever had a completed (>26-week) pregnancy

1990 (81.3%)

1677 (83.4%)

313 (71.6%)

Among parous women

N = 1990

N = 1677

 

N = 313

 Mean number of completed pregnancies (SD)

2.7 (1.5)

2.8 (1.6)

2.2 (1.1)

 Mean age at first completed pregnancy (SD)

23.2 (5.7)

22.5 (5.3)

27.1 (6.2)

 Ever breastfed

1242 (62.4%)

967 (57.7%)

275 (87.9%)

 Mean duration of breastfeeding among those who breastfed, months (SD)

12.1 (15.0)

10.9 (14.4)

16.2 (16.5)

  1. aIncluding those who also served as controls in the Women’s BCIS. Triple-negative = estrogen receptor (ER)–/progesterone receptor (PR)–/human epidermal growth factor receptor-2 (HER2)–, Luminal A-like = ER+ and/or PR+ plus HER2–, Luminal B-like = ER+ and/or PR+ plus HER2+, HER2-enriched = ER–/ PR–/HER2+. CARE Contraceptive and Reproductive Experiences Study, BCIS Breast Carcinoma in situ Study, LIFE Learning the Influence of Family and Environment Study