Table 3.
Immunohistochemical subtypes of bilateral breast cancers.
| Characteristic | Description | n (%) |
|---|---|---|
| IHC by the number of the affected breasts | Unknown | 75 (12.2%) |
| IHC available | 539 (87.8%) | |
| HR+ HER2− | 379 (70.3%) 1 | |
| HR+ HER2+ | 66 (12.2%) 1 | |
| HR− HER2+ | 42 (7.8%) 1 | |
| HR− HER2− | 52 (9.6%) 1 | |
| Total | 614 (100%) | |
| Bilaterally concordant expression | ||
| IHC by the number of the affected patients | HR+ HER2− | 143 (82.2%) 2 |
| HR+ HER2+ | 13 (7.5%) 2 | |
| HR− HER2+ | 7 (4.0%) 2 | |
| HR− HER2− | 11 (6.3%) 2 | |
| Total concordant cases | 174 (56.7%) | |
| Bilaterally disconcordant expression | ||
| HR+ HER2−/HR+ HER2+ | 24 (34.3%) 3 | |
| HR+ HER2−/HR− HER2+ | 15 (21.4%) 3 | |
| HR+ HER2−/HR− HER2− | 20 (28.6%) 3 | |
| HR+ HER2+/HR− HER2+ | 3 (4.3%) 3 | |
| HR+ HER2+/HR− HER2− | 5 (7.1%) 3 | |
| HR− HER2+/HR− HER2− | 3 (4.3%) 3 | |
| Total discordant cases | 70 (22.8%) | |
| Unknown4 | 63 (20.5%) |
1 The percentage out of all IHC available cases. 2 The percentage out of bilaterally concordant cases. 3 The percentage out of bilaterally known cases. 4Patient with unavailable IHC results from either side of the diseased breast is considered unknown, even if the IHC result on one side is known.