RRM1 and neoplasm: The differential expression/co-expression of several genes such as excision repair cross-complementing 1 (ERCC1), ribonucleotide reductase subunit M1 (RRM1), thymidylate synthase (TYMS), class III β-tubulin (TUBβ3), DNA topoisomerase I and II alpha (TOP1 and TOP2α), glutathione S-transferase Pi 1 (GSTP1), etc. in tumor tissues is closely related to chemoresistance and prognosis in cancer patients.