Several studies have highlighted that RRM2 is overexpressed in various human malignancies such as prostate cancer [35], neuroblastoma [23], glioblastoma [14], breast cancer [40], etc. Moreover, upregulation of RRM2 has been associated with tumor angiogenesis, metastasis, and progression, as well as poor prognosis of patients [20–22]. This evidence concerns the gene RRM2 and breast cancer.