NDRG1 and breast carcinoma: Based on the meta-analysis of three studies, no correlation between NDRG1 protein expression and PR status was identified (P = 0.41, log OR: -0.82, 95% CI: -2.77-1.14, I2: 88.57%, 218 breast cancer with PR positive/270 breast cancer with PR negative, 3 studies, Fig. 7).