Table 1 Descriptive statistics based on percentage density
From: Possible influence of mammographic density on local and locoregional recurrence of breast cancer
| Â | All cases (n= 1,774) | |||
|---|---|---|---|---|
| Â | Unadjusted | Age-adjusted | ||
|  | PD <25% ( n = 1,329) | PD ≥25% ( n = 445) | P value | P value |
Age at mammography, years | 63.1 | 59.0 | <0.001 | Â |
Body mass index | 26.4 | 23.9 | <0.001 | <0.001 |
Age at menarche, years | 13.6 | 13.5 | 0.719 | 0.310 |
Oral contraceptive use | Â | Â | <0.001 | 0.484 |
   Yes | 410 (31%) | 184 (41%) |  |  |
   No | 914 (69%) | 261 (59%) |  |  |
Parity and age at first birth | Â | Â | 0.005 | 0.001 |
   Nulliparous | 173 (13%) | 79 (18%) |  |  |
   Parity ≤2 and age at first birth ≤25 | 386 (29%) | 136 (31%) |  |  |
   Parity ≤2 and age at first birth >25 | 403 (30%) | 144 (32%) |  |  |
   Parity >2 and age at first birth ≤25 | 272 (20%) | 63 (14%) |  |  |
   Parity >2 and age at first birth >25 | 96 (7%) | 23 (5%) |  |  |
Breast feeding | Â | Â | 0.174 | 0.069 |
   Yes | 940 (80%) | 316 (77%) |  |  |
   No | 229 (20%) | 93 (23%) |  |  |
Age at menopause, years | 50.4 | 50.5 | 0.506 | 0.046 |
HRT use | Â | Â | <0.001 | <0.001 |
   Never | 974 (74%) | 244 (56%) |  |  |
   Past | 70 (5%) | 70 (16%) |  |  |
   Current | 268 (20%) | 124 (28%) |  |  |
Previous benign breast disease | Â | Â | <0.001 | <0.001 |
   Yes | 161 (12%) | 89 (20%) |  |  |
   No | 1,163 (88%) | 354 (80%) |  |  |
Breast cancer heredity | Â | Â | 0.633 | 0.829 |
   Yes | 200 (15%) | 64 (15%) |  |  |
   No | 1,091 (85%) | 376 (85%) |  |  |