DPYD and esophageal cancer: Although some molecular markers have been identified for personalized treatment of esophageal cancer, such as cisplatin related markers [breast cancer susceptibility gene 1 (BRCA1) and excision repair cross-complementing 1 (ERCC1)], 5-FU related markers [dihydropyrimidine dehydrogenase (DPD) and thymidylatesynthase (TS)] and docetaxel related markers (BRCA1) [5-7], the molecular backgrounds remain largely unclear to determine therapeutic effectiveness in esophageal cancer systematically.