Table 1.
Characteristics and main results of the studies evaluating the prognostic implications of HER2−low status
| Study | Setting | Patients, n | HER2−low (%) | HER2−low in HR + subgroup | HER2−low in HR− subgroup | Main outcomes |
|---|---|---|---|---|---|---|
| Schettini et al. [7] | Metastatic and early | 3,689 | 2,203 (59.7%) | 65.4% | 36.5% | OS: no significant difference between HR+/HER2−low and HR+/HER2 0 (p = 0.234) and between HR−/HER2−low and HR−/HER2 0 (p = 0.533) |
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| Won et al. [14] | Metastatic and early | 30,491 | 9,506 (31.2%) | 33.6% | 23.0% | OS: no difference between HR+/HER2−low and HR+/HER2 0 (p = 0.086) and between HR−/HER2−low and HR−/HER2 0 (p = 0.170) BCSS: higher for HR+/HER2−low than HR+/HER2 0 (99.4% and 99.1 %, p = 0.003) and for HR−/HER2−low than HR−/HER2 0 (97.2% vs. 95.9%, p = 0.023) |
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| Agostinetto et al. [12] | Metastatic and early | 804 | 410 (51%) | 53% | 43.5% | OS: no significant difference between HER2−low/HR+ and HER2 0/HR+ (p = 0.47) and between HER2−Low/HR− and HER2 0/HR−(p = 0.52) DFI and PFI: higher for HER2−low/HR+ than HER2−low/HR− BC (p = 0.01 and p = 0.0066) |
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| Gampenrieder et al. [43] Metastatic and early | 1,729 | 608 (35.2%) | 39.8% | 22.5% | OS: no significant difference between HR+/HER2−low and HR+/HER2 0 (38.9 vs. 38.9 mp = 0.171) and between HR−/HER2−low and HR−/HER2 0 (16.6 vs.12.7 m, p = 0.585) | |
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| Tarantino et al. [13] | Early | 5,235 | 2,917 (55.7%) | 58.2% | 39.3% | OS: no significant difference between HR+/HER2−low and HR+/HER2 0 (p = 0.26) and between HR−/HER2−low and HR−/HER2 0 (p = 0.65) DFS and DDFS: no significant difference between HR+/HER2−low and HR+/HER2 0 (p = 0.11 and p = 0.13) and between HR−/HER2−low and HR−/HER2 0 (p = 0.38 and p = 0.43) pCR: lower rate in HER2−low than HER2 0 (16.6% vs. 26.8%, p = 0.002). No significant difference when restricting analysis to HR + tumors (p = 0.08) |
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| Denkert et al. [11] | Early | 2,310 | 1,098 (47.5%) | 61.2% | 34% | 3y DFS: no significant difference between HR+/HER2−low and HR+/HER2 0 (82.8% vs. 79.3%, p = 0.39), higher for HR−/HER2−low than HR−/HER2 0 (84.5% vs. 74.4%, p = 0.0076) 3y OS: no significant difference between HR+/HER2−low and HR+/HER2 0 (92.3% vs. 88.4%, p = 0.13) and between HR−/HER2−low and HR−/HER2 0 (90.2% vs. 84.3%, p = 0.016) pCR: lower in HER2−low than HER2 0 (29.2% vs. 39.9%, p = 0.0002). Lower in HR+/HER2−low than HR+/HER2 0 (17.5% vs. 23.6%, p = 0.024). Higher in HR−/HER2−low than HR−/HER2 0 (50.1% vs. 48.9%, p = 0.21) |
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| Mutai et al. [44] | Early | 3,608 | 304 (50%) | NA | NA | OS: higher in HER2−low than HER2 0 among patient with high genomic risk (89% vs. 68%, p = 0.01) DFS: higher in HER2−low than HER2 0 among patient with high genomic risk (80% vs. 59%, p = 0.01) DDFS: higher in HER2−low than HER2 0 among patient with high genomic risk (89% vs. 59%, p = 0.002) |
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| Tan et al. [45] | Early | 28,280 | 12,260 (43.4%) | 45.9% | 29.4% | DFS: higher in HER2−low than HER2 0 (p < 0.001) OS: higher in HER2−low than HER2 0 (p < 0.001) |
BCSS, breast cancer-specific survival; DDFS, distant disease-free survival; DFI, disease-free interval; DFS, disease-free survival; HR+, hormone receptor positive; HR−, hormone receptor negative; OS, overall survival; PFI, progression-free interval.