Table 2.
Tumor subtypes and discordances
| Subtypes in Primary Tumor and Brain Metastasis | N | (%) | ||||
|---|---|---|---|---|---|---|
| Total number of cases | 219 | (100) | ||||
| Primary tumor subtype | ||||||
| HR+/HER2+ | 53 | (24.2) | ||||
| HR+/HER2− | 61 | (27.9) | ||||
| HR−/HER2+ | 42 | (19.2) | ||||
| HR−/HER2− | 53 | (24.2) | ||||
| Not determined | 10 | (4.6) | ||||
| Brain metastasis subtype | ||||||
| HR+/HER2+ | 40 | (18.3) | ||||
| HR+/HER2− | 47 | (21.5) | ||||
| HR−/HER2+ | 64 | (29.2) | ||||
| HR−/HER2− | 55 | (25.1) | ||||
| Not determined | 13 | (5.9) | ||||
| Overall discordance | N | (%) | ||||
| Total number of complete cases | 193 | (100) | ||||
| Breast—brain discordance (for any receptor) |
Discordant: 70
Concordant: 123 |
(36.3) (63.7) |
||||
| Breast—brain discordance (leading to a different subtype) |
Discordant: 50
Concordant: 143 |
(22.8) (78.2) |
||||
| Receptor-specific discordance | ||||||
| Receptor | ER | (%) | PR | (%) | HER2 | (%) |
| Total number of cases with determined receptor status | 216 | (100) | 210 | (100) | 201 | (100) |
| Primary tumor receptor status | + 117 | (54.2) | + 79 | (37.6) | + 93 | (46.3) |
| −99 | (45.8) | −131 | (62.4) | −108 | (53.7) | |
| Brain metastasis receptor status | + 89 | (41.2) | + 38 | (18.1) | + 104 | (51.7) |
| −127 | (58.8) | −172 | (81.9) | −97 | (48.3) | |
| Discordant | 36 | (16.7) | 53 | (25.2) | 21 | (10.4) |
| Gain of expression (% of receptor negative primary tumors) | 4 | (4.1) | 6 | (4.6) | 16 | (14.8) |
| Loss of expression (% of receptor positive primary tumors) | 32 | (27.4) | 47 | (59.5) | 5 | (5.4) |
+ = positive; − = negative; ER = estrogen receptor; PR = progesterone receptor; HER2 = human epidermal growth factor receptor 2.