2. Basic characteristics of patients with bilateral breast cancer.
| Basic information | n (%) |
| NA, not applicable; BMI, body mass index; BRCA1/2, breast cancer susceptibility genes1/2. | |
| Age (year) | |
| <55 | 220 (50.0) |
| ≥55 | 212 (48.2) |
| NA | 8 (1.8) |
| Gender | |
| Female | 419 (99.8) |
| Male | 1 (0.2) |
| Family history | |
| Yes | 33 (7.5) |
| No | 407 (92.5) |
| BMI (kg/m2) | |
| <24 | 228 (51.8) |
| 24≤BMI<28 | 142 (32.3) |
| ≥28 | 51 (11.6) |
| NA | 19 (4.3) |
| BRCA1/2 screening | |
| Yes | 15 (3.4) |
| No | 405 (92.1) |
| NA | 20 (4.5) |
| Oncotype DX | |
| Yes | 3 (0.7) |
| No | 417 (99.3) |
| NA | 20 (4.5) |
| Time | |
| Simultaneous | 304 (69.1) |
| Metachronous | 94 (21.4) |
| NA | 42 (9.5) |