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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