Additionally, previous studies reported that obesity was related with more advanced and biologically adverse tumors, such as larger tumor size, more lymph node involvement, higher proportion of ER-negative, triple negative tumors, grade III, or high Ki-67 index, and this could not be reproduced in our study (16, 33, 34), which may be explained by our study only including the luminal population. This evidence concerns the gene MKI67 and obesity disorder.