NDRG1 and breast cancer: Based on the meta-analysis of three studies, there was a positive correlation between NDRG1 protein expression and axillary lymph node metastasis (P = 0.01, log OR: 0.59, 95% CI: 0.13–1.05, I2: 24.24%, 292 breast cancer with axillary lymph node-positive/229 breast cancer with axillary lymph node-negative, 4 studies, Fig. 5).