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Table 1 Demographic and reproductive health characteristics of women with breast cancer (cases) and controls by study

From: Body size in early life and risk of breast cancer

  

KARMA

LIBRO1

Variables

Categories

Cases (n = 2272)

Controls (n = 10,468)

P value*

Cases (n = 4459)

Controls (n = 18237)

P value*

Demographics

 Age at questionnaire, years

Mean ± SD

61.3 ± 9.2

55.7 ± 9.2

<0.001

62.6 ± 9.7

57.4 ± 9.1

<0.001

 Body size at age 7 years, n (%)

Small

1327 (58.4)

5644 (53.9)

<0.001

2727 (61.2)

9870 (54.1)

<0.001

Medium

773 (34.0)

3824 (36.5)

1358 (30.5)

6622 (36.3)

Large

172 (7.6)

1000 (9.6)

374 (8.4)

1745 (9.6)

 Body size at age 18 years, n (%)

Small

705 (31.0)

3042 (29.1)

0.001

1482 (33.3)

5233 (28.7)

<0.001

Medium

1407 (61.9)

6433 (61.5)

2638 (59.2)

11,135 (61.1)

Large

160 (7.0)

992 (9.5)

334 (7.5)

1866 (10.2)

 BMI at questionnaire, kg/m2

Mean ± SD

25.6 ± 4.2

25.2 ± 4.1

<0.001

25.3 ± 4.2

25.2 ± 4.2

0.071

Reproductive health factors

 Age at menarche, years

Mean ± SD

13.2 ± 1.5

13.2 ± 1.5

0.735

13.1 ± 1.5

13.1 ± 1.5

0.398

 Number of children, n (%)

Nulliparous

407 (13.1)

1574 (11.8)

0.018

673 (15.1)

2599 (14.3)

<0.001

1

502 (16.1)

1910 (14.3)

790 (17.7)

2746 (15.1)

2

1463 (46.9)

6425 (48.2)

1975 (44.3)

8425 (46.2)

≥3

743 (23.9)

3430 (25.7)

1021 (22.9)

4467 (24.5)

 Menopause status, n (%)

Postmenopause

1999 (87.9)

6733 (64.3)

<0.001

4229 (94.8)

13,143 (72.1)

<0.001

Premenopause

273 (12.0)

3735 (35.7)

230 (5.2)

5094 (27.9)

 Ever used HRT, n (%)

Yes

882 (38.8)

3025 (28.9)

<0.001

2381 (53.4)

6225 (34.1)

<0.001

No

1390 (61.2)

7443 (71.1)

2078 (46.6)

12,012 (65.9)

 Family history of breast cancer, n (%)

Yes

487 (21.4)

1431 (13.7)

<0.001

900 (20.2)

2426 (13.3)

<0.001

No

1785 (78.6)

9037 (86.3)

3559 (75.4)

15,811 (86.7)

  1. SD standard deviation, BMI body mass index, HRT hormone replacement therapy. *P values were derived from chi-square tests for categorical variables and from the independent sample t test for continuous variables