POLE2 and hairy cell leukemia: Among these genes, only proteins of two candidate gene FPGS and POLE2 currently have small-molecule drugs indicated for cancer therapy, i.e., raltitrexed for malignant neoplasm of colon and rectum and cladribine for lymphoproliferative diseases such as hairy cell leukemia, Non-Hodgkin's lymphoma, etc. Together, these results indicate great repositioning potential of candidate genes as drug targets for anti-neoplastic purposes in breast cancer.