Table 2. Results of the meta-analysis on the prognostic effects of immune checkpoint molecules in HNC patients.
| Variable | Study no. | Sample size | HR (95% CI) | P value | Heterogeneity | ||
| I2 | P value | ||||||
| OS | Overall | 43 | 6225 | 0.964 (0.791-1.175) | 0.714 | 74.8% | <0.001 |
| Immune checkpoint molecules | |||||||
| PD-L1 | 32 | 4854 | 0.874 (0.711-1.073) | 0.197 | 72.8% | <0.001 | |
| PD-1 | 7 | 967 | 0.926 (0.424-2.025) | 0.848 | 76.7% | <0.001 | |
| IDO | 4 | 404 | 2.197 (1.199-4.023) | 0.011 | 59.8% | 0.059 | |
| Ethnicity | |||||||
| Asian | 19 | 2938 | 0.923 (0.651-1.307) | 0.650 | 77.1% | <0.001 | |
| Caucasian | 24 | 3287 | 0.995 (0.779-1.270) | 0.965 | 73.8% | <0.001 | |
| Tumor location | |||||||
| OSCC | 13 | 1477 | 0.879 (0.586-1.317) | 0.532 | 85.0% | <0.001 | |
| NPC | 10 | 1008 | 0.862 (0.618-1.203) | 0.383 | 33.7% | 0.139 | |
| OPSCC | 4 | 592 | 0.878 (0.532-1.450) | 0.611 | 47.1% | 0.129 | |
| HPSCC | 1 | 83 | 1.300 (0.700-2.415) | 0.407 | - | - | |
| SSCC | 1 | 53 | 1.355 (0.739-2.485) | 0.326 | - | - | |
| LSCC | 2 | 447 | 1.517 (0.252-9.126) | 0.649 | 91.4% | 0.001 | |
| Sample size | |||||||
| Large | 14 | 3721 | 1.044 (0.803-1.356) | 0.748 | 74.0% | <0.001 | |
| Small | 29 | 2504 | 0.915 (0.687-1.220) | 0.546 | 74.3% | <0.001 | |
| DFS | Overall | 19 | 2901 | 1.097 (0.733-1.642) | 0.652 | 92.5% | <0.001 |
| Inhibitory immune checkpoint molecules | |||||||
| PD-L1 | 13 | 2010 | 0.874 (0.523-1.459) | 0.606 | 94.1% | <0.001 | |
| IDO | 2 | 258 | 1.725 (0.611-4.869) | 0.303 | 59.5% | 0.116 | |
| PD-1 | 4 | 633 | 1.931 (0.716-5.211) | 0.194 | 87.5% | <0.001 | |
| Ethnicity | |||||||
| Asian | 8 | 1252 | 1.131 (0.506-2.533) | 0.764 | 93.6% | <0.001 | |
| Caucasian | 11 | 1649 | 1.060 (0.760-1.479) | 0.731 | 73.9% | <0.001 | |
| Tumor location | |||||||
| OSCC | 3 | 247 | 0.609 (0.208-1.788) | 0.367 | 70.8% | 0.033 | |
| NPC | 6 | 666 | 1.339 (0.581-3.085) | 0.494 | 92.5% | <0.001 | |
| SSCC | 1 | 53 | 1.834 (0.955-3.522) | 0.068 | - | - | |
| OPSCC | 1 | 181 | 1.090 (0.783-1.518) | 0.610 | - | - | |
| LSCC | 2 | 447 | 1.282 (0.242-6.783) | 0.770 | 85.9% | 0.008 | |
| Sample size | |||||||
| Large | 6 | 1756 | 0.844 (0.595-1.198) | 0.343 | 75.5% | <0.001 | |
| Small | 13 | 1145 | 1.225 (0.764-1.963) | 0.399 | 88.9% | <0.001 | |
| PFS | Overall | 6 | 545 | 0.996 (0.585-1.685) | 0.989 | 68.5% | 0.007 |
| Inhibitory immune checkpoint molecules | |||||||
| PD-L1 | 6 | 545 | 0.891 (0.565-1.404) | 0.989 | 68.5% | 0.007 | |
| Ethnicity | |||||||
| Asian | 3 | 233 | 0.846 (0.492-1.455) | 0.744 | 48.3% | 0.144 | |
| Caucasian | 3 | 312 | 1.218 (0.372-3.993) | 0.546 | 82.7% | 0.003 | |
| Tumor location | |||||||
| NPC | 2 | 227 | 0.762 (0.506-1.149) | 0.195 | 0.0% | 0.935 | |
| OSCC | 1 | 84 | 0.576 (0.308-1.076) | 0.084 | - | - | |
| HPSCC | 1 | 83 | 1.350 (0.740-2.463) | 0.328 | - | - | |
| Sample size | |||||||
| Large | 1 | 161 | 0.770 (0.480-1.235) | 0.279 | - | - | |
| Small | 5 | 384 | 1.067 (0.536-2.125) | 0.853 | 73.0% | 0.005 | |
| DSS | Overall | 5 | 699 | 0.779 (0.330-1.839) | 0.569 | 84.7% | <0.001 |
| DMFS | Overall | 3 | 361 | 0.599 (0.346-1.035) | 0.066 | 0.0% | 0.604 |