Table 2.
Subgroup analyses for survival at 1, 2, 3, and 5 years
| Outcomes | Factors | Groups | Number of studies | Incidence and 95% CI | P value | I2 (%) | P value for Q statistic | P value between subgroups |
|---|---|---|---|---|---|---|---|---|
| 1-year survival rate | Sample size | ≥ 50 | 3 | 0.74 (0.42–1.00) | < 0.001 | 98.3 | < 0.001 | < 0.001 |
| < 50 | 4 | 0.46 (0.15–0.78) | 0.004 | 89.8 | < 0.001 | |||
| Mean age (years) | ≥ 65 | 4 | 0.67 (0.41–0.94) | < 0.001 | 97.1 | < 0.001 | < 0.001 | |
| < 65 | 3 | 0.44 (0.35–0.53) | < 0.001 | 0.0 | 0.622 | |||
| Male (%) | ≥ 90 | 3 | 0.36 (0.04–0.67) | 0.026 | 79.8 | 0.007 | < 0.001 | |
| < 90 | 4 | 0.74 (0.48–1.00) | < 0.001 | 97.7 | < 0.001 | |||
| Stage III–IV (%) | ≥ 50 | 3 | 0.64 (0.21–1.00) | 0.004 | 98.4 | < 0.001 | < 0.001 | |
| < 50 | 3 | 0.56 (0.19–0.93) | 0.003 | 95.8 | < 0.001 | |||
| Interval from prior therapy to RT | ≥ 24 | 3 | 0.79 (0.55–1.00) | < 0.001 | 90.0 | < 0.001 | < 0.001 | |
| < 24 | 2 | 0.27 (− 0.04 to 0.57) | 0.088 | 88.0 | 0.004 | |||
| Study quality | Moderate | 3 | 0.86 (0.70–1.00) | < 0.001 | 90.8 | < 0.001 | < 0.001 | |
| Low | 4 | 0.37 (0.18–0.56) | < 0.001 | 73.5 | 0.010 | |||
| 2-year survival rate | Sample size | ≥ 50 | 3 | 0.25 (0.10–0.39) | 0.001 | 82.1 | 0.004 | 0.576 |
| < 50 | 3 | 0.26 (0.16–0.36) | < 0.001 | 0.0 | 0.743 | |||
| Mean age (years) | ≥ 65 | 2 | 0.34 (0.18–0.50) | < 0.001 | 68.1 | 0.077 | 0.010 | |
| < 65 | 4 | 0.19 (0.13–0.25) | < 0.001 | 0.0 | 0.523 | |||
| Male (%) | ≥ 90 | 2 | 0.27 (0.11–0.42) | 0.001 | 0.0 | 0.444 | 0.696 | |
| < 90 | 4 | 0.25 (0.14–0.35) | < 0.001 | 73.5 | 0.010 | |||
| Stage III–IV (%) | ≥ 50 | 2 | 0.22 (0.13–0.30) | < 0.001 | 7.2 | 0.299 | 0.635 | |
| < 50 | 3 | 0.27 (0.11–0.43) | 0.001 | 80.1 | 0.006 | |||
| Interval from prior therapy to RT | ≥ 24 | 2 | 0.24 (0.13–0.36) | < 0.001 | 0.0 | 0.591 | 0.006 | |
| < 24 | 2 | 0.18 (0.11–0.24) | < 0.001 | 0.0 | 0.430 | |||
| Study quality | Moderate | 3 | 0.27 (0.11–0.43) | 0.001 | 80.1 | 0.006 | 0.365 | |
| Low | 3 | 0.21 (0.14–0.28) | < 0.001 | 0.0 | 0.558 | |||
| 3-year survival rate | Sample size | ≥ 50 | 3 | 0.29 (0.01–0.57) | 0.045 | 97.6 | < 0.001 | 0.007 |
| < 50 | 2 | 0.17 (0.07–0.27) | 0.001 | 0.0 | 0.983 | |||
| Mean age (years) | ≥ 65 | 3 | 0.31 (0.06–0.56) | 0.015 | 95.5 | < 0.001 | < 0.001 | |
| < 65 | 2 | 0.12 (0.05–0.18) | < 0.001 | 0.0 | 0.740 | |||
| Male (%) | ≥ 90 | 1 | 0.17 (− 0.13 to 0.46) | 0.273 | – | – | 0.381 | |
| < 90 | 4 | 0.26 (0.04–0.48) | 0.023 | 96.6 | < 0.001 | |||
| Stage III–IV (%) | ≥ 50 | 2 | 0.32 (− 0.08 to 0.73) | 0.119 | 98.7 | < 0.001 | 0.004 | |
| < 50 | 2 | 0.19 (0.12–0.27) | < 0.001 | 0.0 | 0.539 | |||
| Interval from prior therapy to RT | ≥ 24 | 3 | 0.30 (0.01–0.59) | 0.042 | 94.3 | < 0.001 | < 0.001 | |
| < 24 | 2 | 0.16 (0.06–0.26) | 0.002 | 59.9 | 0.114 | |||
| Study quality | Moderate | 3 | 0.31 (0.06–0.56) | 0.015 | 95.5 | < 0.001 | < 0.001 | |
| Low | 2 | 0.12 (0.05–0.18) | < 0.001 | 0.0 | 0.740 | |||
| 5-year survival rate | Sample size | ≥ 50 | 3 | 0.16 (− 0.03 to 0.35) | 0.102 | 96.4 | < 0.001 | < 0.001 |
| < 50 | 2 | 0.12 (− 0.11 to 0.36) | 0.294 | 84.6 | 0.011 | |||
| Mean age (years) | ≥ 65 | 2 | 0.17 (− 0.12 to 0.46) | 0.255 | 98.5 | < 0.001 | 0.031 | |
| < 65 | 3 | 0.11 (0.01–0.21) | 0.032 | 67.0 | 0.048 | |||
| Male (%) | ≥ 90 | 1 | 0.26 (0.08–0.44) | 0.004 | – | – | 0.074 | |
| < 90 | 4 | 0.12 (− 0.01 to 0.26) | 0.077 | 96.1 | < 0.001 | |||
| Stage III–IV (%) | ≥ 50 | 3 | 0.21 (− 0.01 to 0.42) | 0.062 | 96.5 | < 0.001 | < 0.001 | |
| < 50 | 2 | 0.05 (− 0.03 to 0.14) | 0.215 | 60.5 | 0.112 | |||
| Interval from prior therapy to RT | ≥ 24 | 2 | 0.17 (− 0.12 to 0.46) | 0.255 | 98.5 | < 0.001 | 0.009 | |
| < 24 | 2 | 0.06 (0.01–0.12) | 0.027 | 23.4 | 0.253 | |||
| Study quality | Moderate | 3 | 0.15 (− 0.06 to 0.36) | 0.156 | 97.1 | < 0.001 | 0.019 | |
| Low | 2 | 0.14 (− 0.07 to 0.34) | 0.202 | 80.8 | 0.023 |