SIX4 and non-small cell lung carcinoma: The Kaplan-Meier curves showed that SIX2 and SIX6 expressions predicted poor RFS of patients diagnosed as NSCLC (SIX2: pooled HR = 1.83, 95 % CI, 1.51–2.22, p < 0.001; SIX6: pooled HR = 1.88, 95 % CI, 1.55–2.29, p < 0.001; Fig. 7g, i), while SIX4 had no significant effect (pooled HR = 1.05, 95 % CI, 0.8–1.37, p = 0.74; Fig. 7h).