By performing the LASSO Cox regression analysis with 9 candidate genes in breast cancer patients of TCGA-BRCA training dataset, 5 pivotal genes were unearthed to establish the prognostic signature, Lactate Metabolism Index, namely LMI (Figures 2A, B), including RPS14, SLC19A1, CYC1, RRM2B, OCRL. This evidence concerns the gene RRM2B and breast cancer.