MKI67 and lung cancer: The pooled HR of the total population for OS was 1.122 (95%CIs: 1.089–1.156, Z = 7.56, P < 0.001; I2 = 78.20%, P < 0.001, Figs. 2, 3 and 4), showing that a high Ki-67 level indicates worse outcome for lung cancer patients.