SIX4 and non-small cell lung carcinoma: The Kaplan-Meier curves indicated that patients with higher mRNA levels of SIX2, SIX4, and SIX6 had unfavorable OS time, which represent poor survival in NSCLC (SIX2: pooled HR = 1.35, 95 % CI, 1.18–1.53, p < 0.001; SIX4: pooled HR = 1.22, 95 % CI, 1.03–1.44, p = 0.022; SIX6: pooled HR = 1.23, 95 % CI, 1.08–1.39, p = 0.0017; Fig. 6g–i).