Abstract: Cancer is now the second leading cause of death after cardiovascular diseases. Although there are many different cancer treatments available, all of them have serious side effects and drug resistance. Therefore, scientists are searching for natural products that can effectively prevent the occurrence of cancers. Studies have shown that the consumption of citrus fruits can reduce the risk of several diseases, including cancers, and its anti-cancer effects are attributed to a variety of bioactive ingredients. This article systematically summarizes recent progress in research on the major anti-cancer ingredients in citrus fruits and their molecular mechanisms. Citrus is one of the important fruits with high medicinal value. In-depth studies on its anti-cancer effects and molecular mechanisms will help to enhance its industrial value, and provide a theoretical basis for the processing and development of citrus fruits into functional foods for chemical prevention of cancers. As the anti-cancer constituents and mechanisms of citrus fruits have been understood fully, their application as a natural source of anti-cancer agents in clinical cancer treatments can be expected soon.

Key words: citrus; anticancer; bioactive ingredients; anticancer mechanism