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Table 1 The sociodemographic characteristics between early-onset and late-onset breast cancer participants

From: Association of early-onset breast cancer with body mass index, menarche, and menopause in Taiwan

Characteristics, n (%)

Early-onset

(≤ 40 years old)

(n = 131)

Late-onset

(> 40 years old)

(n = 644)

P-valuesa

P-values after Bonferroni correction

Age at diagnosis (year), mean ± SD

35.87 ± 4.13

54.24 ± 8.68

 < 0.001

 < 0.001

BMI (kg/m2)

  

 < 0.001

 < 0.001

  BMI < 24

100 (76.3)

361 (56.1)

  

  BMI ≥ 24

31 (23.7)

282 (43.9)

  

Education

  

 < 0.001

 < 0.001

  < college

43 (32.8)

438 (68.0)

  

  ≥ college

88 (67.2)

206 (32.0)

  

Marriage

  

 < 0.001

 < 0.001

  Unmarried/Divorce/Widowed

49 (37.4)

125 (19.4)

  

  Married

82 (62.6)

519 (80.6)

  

Smoking state

  

0.677

1.000

  Never

124 (94.7)

615 (95.5)

  

  Ever

7 (5.3)

29 (4.5)

  

Alcohol intake

  

1.000

1.000

  Never

128 (97.7)

627 (97.4)

  

  Ever

3 (2.3)

17 (2.6)

  

Physical activity

  

0.035

0.875

  None

67 (51.1)

265 (41.1)

  

  Yes

64 (48.9)

379 (58.9)

  

Menopausal status

  

 < 0.001

 < 0.001

  Premenopause

79 (60.3)

108 (16.8)

  

  Peri-/Postmenopause

52 (39.7)

536 (83.2)

  

BMI < 24

  

 < 0.001

 < 0.001

  Premenopause

67 (67.0)

65 (18)

  

  Peri-/Postmenopause

33 (33.0)

296 (82)

  

BMI ≥ 24

  

0.001

0.025

  Premenopause

12 (38.7)

43 (15.2)

  

  Peri-/Postmenopause

19 (61.3)

239 (84.8)

  

Oral contraceptive use

  

0.149

1.000

  Never

119 (90.8)

555 (86.2)

  

  Ever

12 (9.2)

89 (13.8)

  

Parity

  

 < 0.001

 < 0.001

  Nulliparous

52 (39.7)

79 (12.3)

  

  Parous

79 (60.3)

565 (87.7)

  

Number of births

  

0.001

0.025

  One

21 (26.6)

72 (12.7)

  

  More than one

58 (73.4)

493 (87.3)

  

Age at first birth

  

 < 0.001

0.001

  < 27 years

23 (29.1)

303 (53.7)

  

  ≥ 27 years

56 (70.9)

261 (46.3)

  

Lactation history

  

0.003

0.075

  Never

21 (26.6)

251 (44.4)

  

  Ever

58 (73.4)

314 (55.6)

  

Fried food

  

 < 0.001

 < 0.001

  1 ~ 2 times a week

113 (86.3)

619 (96.1)

  

  3 ~ 6 times a week

18 (13.7)

25 (3.9)

  

Benign breast disease

  

0.559

1.000

  Never

98 (74.8)

497 (77.2)

  

  Ever

33 (25.2)

147 (22.8)

  

Family history of BC

  

0.073

1.000

  None

96 (73.3)

517 (80.3)

  

  Yes

35 (26.7)

127 (19.7)

  
  1. SD Standard deviation, BMI Body mass index
  2. aP-values were calculated for continuous variables by Independent sample t-test and for categorical variables by Chi-square test or Fisher's exact test