As shown in Fig. 3a, high expression level of HIF-1α significantly predicted unfavorable OS in bone tumor (HR = 2.61, 95% CI 2.11–3.23, P <  0.001), without any heterogeneity in the data (fixed effects model: χ2 = 5.70, I2 = 0, P = 0.770). The gene discussed is HIF1A; the disease is bone neoplasm.