Table 2.
Cox regression analyses of relapse-free survival and overall survival by HER2 and hormone receptor status
| Centre-adjusted | Multivariable-adjusteda | |||||
|---|---|---|---|---|---|---|
| Hazard ratio (95% CI) | P | P(int) | Hazard ratio (95% CI) | P | P(int) | |
| Relapse-free survival | ||||||
| Overall: HER2-low vs HER2-zero | 0.88 (0.82–0.93) | < 0.001 | – | 0.90 (0.85–0.96) | 0.002 | – |
| Hormone receptor-positive: HER2-low vs HER2-zero | 0.92 (0.86–0.99) | 0.022 | 0.973 | 0.90 (0.84–0.97) | 0.004 | 0.715 |
| Hormone receptor-negative: HER2-low vs HER2-zero | 0.92 (0.81–1.05) | 0.226 | 0.92 (0.81–1.05) | 0.244 | ||
| Overall: HER2 IHC1+ vs HER2-zero | 0.85 (0.79–0.91) | < 0.001 | – | 0.89 (0.83–0.96) | 0.001 | – |
| Overall: HER2 IHC2+ ISH− vs HER2-zero | 0.96 (0.87–1.06) | 0.421 | 0.94 (0.85–1.05) | 0.280 | ||
| Hormone receptor-positive: HER2 IHC1+ vs HER2-zero | 0.89 (0.82–0.96) | 0.004 | 0.962 | 0.89 (0.82–0.96) | 0.003 | 0.934 |
| Hormone receptor-positive: HER2 IHC2+ ISH− vs HER2-zero | 1.01 (0.90–1.13) | 0.898 | 0.94 (0.83–1.05) | 0.280 | ||
| Hormone receptor-negative: HER2 IHC1+ vs HER2-zero | 0.88 (0.76–1.03) | 0.107 | 0.91 (0.78–1.05) | 0.206 | ||
| Hormone receptor-negative: HER2 IHC2+ ISH− vs HER2-zero | 1.04 (0.83–1.30) | 0.735 | 0.97 (0.78–1.22) | 0.807 | ||
| Overall survival | ||||||
| Overall: HER2-low vs HER2-zero | 0.82 (0.76–0.89) | < 0.001 | – | 0.86 (0.79–0.93) | < 0.001 | – |
| Hormone receptor-positive: HER2-low vs HER2-zero | 0.89 (0.81–0.97) | 0.012 | 0.401 | 0.87 (0.79–0.96) | 0.004 | 0.538 |
| Hormone receptor-negative: HER2-low vs HER2-zero | 0.82 (0.69–0.96) | 0.017 | 0.82 (0.70–0.97) | 0.018 | ||
| Overall: HER2 IHC1+ vs HER2-zero | 0.79 (0.73–0.87) | < 0.001 | – | 0.85 (0.78–0.93) | 0.001 | – |
| Overall: HER2 IHC2+ ISH− vs HER2-zero | 0.91 (0.79–1.04) | 0.148 | 0.88 (0.76–1.01) | 0.062 | ||
| Hormone receptor-positive: HER2 IHC1+ vs HER2-zero | 0.86 (0.78–0.96) | 0.005 | 0.627 | 0.86 (0.78–0.95) | 0.004 | 0.811 |
| Hormone receptor-positive: HER2 IHC2+ ISH− vs HER2-zero | 0.96 (0.82–1.12) | 0.632 | 0.89 (0.76–1.05) | 0.171 | ||
| Hormone receptor-negative: HER2 IHC1+ vs HER2-zero | 0.78 (0.65–0.94) | 0.009 | 0.82 (0.68–0.99) | 0.035 | ||
| Hormone receptor-negative: HER2 IHC2+ ISH− vs HER2-zero | 0.94 (0.71–1.24) | 0.654 | 0.83 (0.62–1.09) | 0.178 | ||
int interaction between HER2 and hormone-receptor status
aCovariates adjusted were study centre, age at diagnosis, ethnicity, year of diagnosis, histology, overall stage, hormone-receptor status, grade, received radiotherapy, endocrine therapy and chemotherapy