Among these essential pathways is overexpression of ATP-binding cassette (ABC) transporters to actively remove chemotherapeutic drugs from cancer cells; changes in metabolism through enzymes such as cytochrome P450 (CYP) and glutathione S-transferases (GSTs) to modulate inactivation and clearance of drugs; augmented DNA repair pathways, including base excision repair (BER) and nucleotide excision repair (NER) pathways, to reverse therapy-induced DNA damage in tumor cells. This evidence concerns the gene HPGDS and neoplasm.