Doxifluridine, also known as 5-Fluoro-2′-deoxyuridine, is a nucleoside analog with potential antineoplastic activity. It is converted to its active form, 5-fluorouracil (5-FU), in tumor cells, where it inhibits DNA synthesis and induces cell death. Doxifluridine may be used in the treatment of various cancers, including colorectal cancer, when other treatments are not effective.