In 1957, Heidelberger et al. [95] first designed and found that the fluoride obtained by replacing the 5th hydrogen atom of uracil with a fluorine atom of similar size is not only similar in volume to the original compound, but also the C-F bond formed is very stable, which is not easy to decompose in the metabolic process and can interfere with normal metabolism at the molecular level. Since then, the anti metabolic tumor drug 5-FU came out and was quickly successfully applied in clinic, which opened the prelude to the anti-tumor effect of anti metabolic drugs.