Table 2. Univariable analysis for progression-free survival.
AJCC, American Joint Committee on Cancer; MBC, metaplastic breast cancer; N, number of patients; HR, hazard ratio; CI, confidence interval; NA, not applicable; Ref, reference; ECOG, Eastern Cooperative Oncology Group; HER2, human epidermal growth factor receptor 2
^Four patients were excluded from survival analysis due to missing information such as the date of diagnosis, last follow-up, or date of death.
*Progression was treated as an event and death as a competing risk event.
#Other histology in our study includes ductal carcinoma in situ micropapillary pattern, heterologous type with matrix production, high-grade metaplastic carcinoma, large cells with intermingling mature plasma cells, matrix-producing carcinoma, and sarcomatoid features, and metaplastic carcinoma.
| Variable | Variable level | N^ | Number of events* | One-year rate (% (range)) | Two-year rate (% (range)) | Five-year rate (% (range)) | HR (95% CI) | p-value |
| Race | Black | 31 | 13 | 94% (77%-98%) | 71% (52%-84%) | 61% (41%-75%) | Ref | |
| White | 97 | 35 | 86% (77%-92%) | 73% (62%-81%) | 60% (48%-70%) | 0.93 (0.49-1.76) | 0.83 | |
| Lymphovascular invasion | No | 77 | 23 | 91% (81%-95%) | 81% (70%-88%) | 65% (51%-75%) | Ref | |
| Yes | 27 | 13 | 89% (69%-96%) | 64% (43%-80%) | 56% (34%-73%) | 1.62 (0.81-3.24) | 0.17 | |
| ECOG performance status | 0 | 74 | 18 | 94% (86%-98%) | 85% (75%-92%) | Ref | ||
| 1 | 37 | 12 | 89% (74%-96%) | 78% (61%-88%) | 1.40 (0.67-2.91) | 0.37 | ||
| 2 | 12 | 12 | 58% (27%-80%) | 17% (3%-41%) | 12.19 (5.44-27.30) | <0.001 | ||
| 3 | 9 | 7 | 67% (28%-88%) | 22% (3%-51%) | 8.46 (3.31-21.60) | <0.001 | ||
| p63 | Negative | 89 | 35 | 87% (78%-93%) | 70% (59%-78%) | 59% (48%-69%) | Ref | |
| Positive | 43 | 14 | 88% (73%-95%) | 78% (62%-88%) | 64% (45%-78%) | 0.92 (0.49-1.71) | 0.78 | |
| AJCC stage | I | 25 | 7 | 92% (72%-98%) | 88% (76%-100%) | 68% (51%-91%) | Ref | |
| II | 81 | 21 | 91% (82%-96%) | 82% (73%-91%) | 72% (62%-83%) | 1.05 (0.45-2.48) | 0.90 | |
| III | 19 | 14 | 94% (67%-99%) | 39% (22%-69%) | 27% (12%-59%) | 4.17 (1.67-10.40) | 0.002 | |
| IV | 7 | 7 | 14% (1%-46%) | 44.64 (13.40-148.71) | <0.001 | |||
| Hormonal therapy | No | 100 | 36 | 88% (79%-93%) | 74% (64%-82%) | 62% (51%-72%) | Ref | |
| Yes | 24 | 9 | 91% (70%-98%) | 74% (51%-87%) | 59% (35%-76%) | 1.04 (0.50-2.17) | 0.91 | |
| Radiation therapy | No | 53 | 19 | 81% (67%-89%) | 71% (57%-82%) | 63% (47%-75%) | Ref | |
| Yes | 74 | 28 | 93% (84%-97%) | 73% (61%-82%) | 60% (47%-70%) | 0.99 (0.55-1.77) | 0.97 | |
| Chemotherapy type | Anthracycline | 68 | 21 | 93% (83%-97%) | 80% (69%-88%) | 70% (56%-80%) | Ref | |
| Non-anthracycline | 36 | 13 | 85% (68%-94%) | 73% (55%-85%) | 56% (35%-72%) | 1.48 (0.74-2.98) | 0.27 | |
| Surgery | Mastectomy | 74 | 28 | 89% (79%-94%) | 74% (62%-82%) | 61% (48%-72%) | Ref | |
| Lumpectomy | 48 | 13 | 96% (84%-99%) | 82% (68%-91%) | 69% (52%-81%) | 0.66 (0.34-1.28) | 0.22 | |
| Histologic subtypes | Spindle cell | 27 | 11 | 92% (73%-98%) | 73% (51%-86%) | 56% (33%-74%) | Ref | |
| Squamous | 40 | 19 | 82% (67%-91%) | 65% (48%-78%) | 54% (37%-68%) | 1.15 (0.55-2.42) | 0.71 | |
| Mixed MBC/mesenchymal | 54 | 16 | 88% (76%-95%) | 76% (62%-86%) | 66% (50%-78%) | 0.69 (0.32-1.49) | 0.34 | |
| #Other | 11 | 3 | 91% (51%-99%) | 82% (45%-95%) | 72% (35%-90%) | 0.54 (0.15-1.95) | 0.35 | |
| Estrogen receptor | No | 111 | 41 | 88% (80%-93%) | 73% (63%-80%) | 61% (50%-70%) | Ref | |
| Yes | 21 | 8 | 86% (62%-95%) | 71% (47%-86%) | 61% (36%-78%) | 1.00 (0.47, 2.14) | > 0.99 | |
| Progesterone receptor | No | 121 | 46 | 86% (79%-91%) | 71% (62%-78%) | 60% (50%-69%) | Ref | |
| Yes | 11 | 3 | 100% (NA) | 90% (47%-99%) | 64% (24%-87%) | 0.66 (0.20-2.11) | 0.48 | |
| HER2 expression | No | 119 | 45 | 87% (79%-92%) | 73% (63%-80%) | 59% (49%-68%) | Ref | |
| Yes | 13 | 4 | 92% (57%-99%) | 69% (37%-87%) | 69% (37%-87%) | 0.76 (0.27-2.12) | 0.60 | |
| Metastasis to the lung | No | 102 | 20 | 95% (88%-98%) | 84% (75%-90%) | Ref | ||
| Yes | 30 | 29 | 63% (44%-78%) | 33% (18%-50%) | 11.41 (6.15-21.18) | <0.001 | ||
| Metastasis to the bone | No | 114 | 31 | 90% (83%-94%) | 79% (70%-85%) | Ref | ||
| Yes | 18 | 18 | 72% (46%-87%) | 33% (14%-55%) | 6.65 (3.60-12.28) | <0.001 | ||
| Metastasis to the brain | No | 123 | 40 | 87% (80%-92%) | 76% (67%-83%) | Ref | ||
| Yes | 9 | 9 | 89% (43%-98%) | 22% (3%-51%) | 5.00 (2.38-10.50) | <0.001 | ||
| Metastasis to the liver | No | 126 | 43 | 89% (81%-93%) | 74% (65%-81%) | Ref | ||
| Yes | 6 | 6 | 67% (19%-90%) | 33% (5%-68%) | 5.16 (2.15-12.36) | <0.001 |