Table 2. Frequencies of combination metastasis sites in breast cancer patients with AJCC stage IV based on different BCS.
| Metastasis site | HR+/HER2- | HR+/HER2+ | HR-/HER2+ | HR-/HER2- | P value |
|---|---|---|---|---|---|
| Number (%) | Number (%) | Number (%) | Number (%) | ||
| Only one site | P < 0.001 | ||||
| Bone | 2172 (27.6) | 412 (5.2) | 128 (1.6) | 248 (3.2) | |
| Lung | 323 (4.1) | 118 (1.5) | 97 (1.2) | 214 (2.7) | |
| Liver | 228 (2.9) | 148 (1.9) | 115 (1.5) | 102 (1.3) | |
| Brain | 37 (0.5) | 13 (0.2) | 14 (0.2) | 40 (0.5) | |
| Two sites | P < 0.001 | ||||
| Bone+Lung | 553 (7.0) | 106 (1.3) | 38 (0.5) | 79 (1.0) | |
| Bone+Liver | 341 (4.3) | 167 (2.1) | 86 (1.1) | 80 (1.0) | |
| Bone+Brain | 90 (1.1) | 33 (0.4) | 13 (0.2) | 13 (0.2) | |
| Lung+Liver | 71 (0.9) | 34 (0.4) | 28 (0.4) | 52 (0.7) | |
| Lung+Brain | 12 (0.2) | 4 (0.05) | 6 (0.08) | 26 (0.3) | |
| Liver+Brain | 8 (0.1) | 5 (0.06) | 4 (0.05) | 3 (0.04) | |
| Three sites | P = 0.098 | ||||
| Bone+Lung+Liver | 224 (2.8) | 89 (1.1) | 50 (0.6) | 55 (0.7) | |
| Bone+Lung+Brain | 49 (0.6) | 16 (0.2) | 10 (0.1) | 15 (0.2) | |
| Bone+Liver+Brain | 24 (0.3) | 12 (0.2) | 7 (0.09) | 9 (0.1) | |
| Liver+Lung+Brain | 4 (0.05) | 2 (0.03) | 5 (0.06) | 6 (0.08) | |
| Four sites | P < 0.001 | ||||
| Bone+Lung+Liver+Brain | 41 (0.5) | 13 (0.2) | 18 (0.2) | 21 (0.3) |