Table 1 Distribution of selected characteristics for 394 study participants, E3N cohort
| Â | All | Control | Case |
|---|---|---|---|
N(%) or Mean (STD) | N(%) or Mean (STD) | N(%) or Mean (STD) | |
All participants | 394 (100) | 197 (100) | 197 (100) |
Menopausal status and age at menopause at baseline | |||
 Pre-menopausal | 78 (19.8) | 39 (19.8) | 39 (19.8) |
 Post-menopausal | 316 (80.2) | 158 (80.2) | 158 (80.2) |
Menopausal status and age at menopause at case’s date of diagnosis | |||
 Pre-menopausal | 3 (0.8) | 2 (1.0) | 1 (0.5) |
 Post-menopausal | 192 (48.7) | 99 (50.3) | 93 (47.2) |
Age (years) at baseline | 56.3 (6.2) | 56.3 (6.2) | 56.3 (6.2) |
Age (years) at case’s date of diagnosis | 68.4 (6.2) | 68.4 (6.2) | 68.4 (6.2) |
BMI (kg/m2) at baseline | |||
  < 25 | 279 (70.8) | 136 (69.0) | 136 (69.0) |
  ≥ 25 | 115 (29.2) | 61 (31.0) | 61 (31.0) |
BMI (kg/m2) at case’s date of diagnosis | |||
  < 25 | 261 (66.2) | 127 (64.5) | 134 (68.0) |
  ≥ 25 | 133 (33.8) | 70 (35.5) | 63 (32.0) |
Total plasma lipid content (ng/L) | 5.4 (0.8) | 5.4 (0.9) | 5.4 (0.8) |
Smoking status at baseline | |||
 Never | 192 (48.7) | 90 (45.7) | 102 (51.8) |
 Ever | 202 (51.3) | 107 (54.3) | 95 (48.2) |
Physical activity (metabolic equivalent tasks (MET)-hour/week) at baseline | |||
  < 35 | 202 (51.3) | 100 (50.8) | 102 (51.8) |
  ≥ 35 | 192 (48.7) | 97 (49.2) | 95 (48.2) |
Education level at baseline | |||
  < BAC | 39 (9.9) | 22 (11.2) | 17 (8.6) |
 BAC to BAC + 2 | 192 (48.7) | 98 (49.7) | 94 (47.7) |
  ≥ BAC + 2 | 163 (41.4) | 77 (39.1) | 86 (43.7) |
Personal history of benign breast disease at baseline | |||
 No | 250 (63.5) | 135 (68.5) | 115 (58.4) |
 Yes | 144 (36.5) | 62 (31.5) | 82 (41.6) |
Family history of breast cancer | |||
 None | 281 (71.3) | 146 (74.1) | 135 (68.5) |
 In first-degree relatives | 61 (15.5) | 31 (15.7) | 30 (15.2) |
 In extended relatives | 52 (13.2) | 20 (10.2) | 32 (16.3) |
Parity and age at first full-term pregnancy (FFTP) | |||
 No children | 57 (14.5) | 22 (11.2) | 35 (17.8) |
 1 or 2 children and < 30 years old at FFTP | 194 (49.2) | 97 (49.2) | 97 (49.2) |
  ≥ 3 children and < 30 years old at FFTP | 108 (27.4) | 62 (31.5) | 46 (23.4) |
  ≥ 30 years old at FFTP | 35 (8.9) | 16 (8.1) | 19 (9.6) |
Total breastfeeding duration | |||
 Never | 152 (38.6) | 79 (40.1) | 73 (37.1) |
  ≤ 6 months | 164 (41.6) | 85 (43.1) | 79 (40.1) |
  > 6 months | 78 (19.8) | 33 (16.8) | 45 (22.8) |
Age at menarche | |||
  < 13 years | 178 (45.2) | 95 (48.2) | 83 (42.1) |
  ≥ 13 years | 216 (54.8) | 102 (51.8) | 114 (57.9) |
Current use of menopausal hormone therapy at baseline | |||
 No | 234 (59.7) | 119 (60.7) | 115 (58.7) |
 Yes | 158 (40.1) | 77 (39.1) | 81 (41.1) |
Use of oral contraceptives at baseline | |||
 Never | 150 (38.1) | 79 (40.1) | 71 (36.0) |
 Ever | 244 (61.9) | 118 (59.9) | 126 (64.0) |
Adherence score to the Healthy dietary pattern | |||
  < median | 197 (50.0) | 89 (45.2) | 108 (54.8) |
  > median | 197 (50.0) | 108 (54.8) | 89 (45.2) |
Adherence score to the Western dietary pattern | |||
  < median | 197 (50.0) | 98 (49.7) | 99 (50.3) |
  > median | 197 (50.0) | 99 (50.3) | 98 (49.7) |