Tegadifur is primarily used in the field of oncology as a chemotherapeutic agent. It is an oral prodrug of 5-fluorouracil (5-FU), which is a well-established antimetabolite in cancer treatment. Tegadifur is specifically designed to improve the bioavailability and reduce the side effects associated with 5-FU. It is commonly prescribed for the treatment of various types of cancers, including colorectal, breast, and gastric cancers. The drug works by inhibiting thymidylate synthase, an enzyme crucial for DNA synthesis, thereby preventing the proliferation of cancer cells. Its oral administration offers convenience and improved patient compliance compared to intravenous therapies. Tegadifur is often used in combination with other chemotherapeutic agents to enhance its efficacy and achieve better clinical outcomes.