| Variable | PFS | OS | ||
| HR (95% CI) | p-value | HR (95% CI) | p-value | |
| Treatment group | ||||
| ST | 1 | 1 | ||
| P-ST | 0.43 (0.29–0.64) | <0.001 | 0.91 (0.60–1.38) | 0.658 |
| PS | ||||
| 0–1 | 1 | 1 | ||
| ≥2 | 1.56 (1.10–2.22) | 0.013 | 2.74 (1.85–4.06) | <0.001 |
| Previous chemotherapy regimens n | ||||
| 0 | 1 | 1 | ||
| 1 | 1.10 (0.69–1.76) | 0.735 | 1.89 (1.16–3.07) | 0.010 |
| ≥2 | 1.98 (1.33–2.95) | 0.001 | 2.86 (1.83–4.46) | <0.001 |
| Previous endocrine therapy regimens n | ||||
| 0 | 1 | 1 | ||
| 1 | 1.42 (0.88–2.28) | 0.147 | 1.19 (0.72–1.97) | 0.495 |
| ≥2 | 1.54 (1.01–2.34) | 0.049 | 1.44 (0.94–2.20) | 0.093 |
| HER2 status | ||||
| Negative | 1 | 1 | ||
| Positive | 1.02 (0.70–1.49) | 0.922 | 1.10 (0.74–1.64) | 0.641 |
| Hormone status | ||||
| Negative | 1 | 1 | ||
| Positive | 0.67 (0.42–1.05) | 0.080 | 0.49 (0.30–0.81) | 0.005 |
| MPE size | ||||
| Small-to-moderate | 1 | 1 | ||
| Moderate-to-large | 1.24 (0.82–1.87) | 0.311 | 0.97 (0.63–1.51) | 0.892 |
| Massive | 1.43 (0.78–2.61) | 0.243 | 1.79 (0.96–3.36) | 0.068 |
Treatment groups and sizes of malignant pleural effusion (MPE) are defined in the Methods section. HR: hazard ratio; ST: systemic therapy; P-ST: pleurodesis followed by ST; PS: performance status; HER: human epidermal growth factor receptor.