SIX1 and non-small cell lung carcinoma: The SIX family genes, especially SIX1, SIX2, SIX3, SIX4, and SIX5, manifested significantly higher expression level in NSCLC tissues than normal lung tissues (SIX1: pooled OR = 15.70, 95 % CI, 10.19–24.19, p = 0.953, and I2 = 0.0 %; SIX2: pooled OR = 4.69, 95 % CI, 3.34–6.59, p = 0.000, and I2 = 78.9 %; SIX3: pooled OR = 1.96, 95 % CI, 1.43–2.68, p = 0.540, and I2 = 0.0 %; SIX4: pooled OR = 20.42, 95 % CI, 12.12–34.41, p = 0.449, and I2 = 0.0 %; SIX5: pooled OR = 2.34, 95 % CI, 1.70–3.22, p = 0.013, and I2 = 65.4 %; Fig. 2a–e).