摘要
Actually, radiation alone is not enough to kill tumor cells efficientlybecause of the radioresistance of tumor cells. It is well known that tumors from the samehistolog-ical origin and of the same development stage are extremely heterogeneous in theirsensitivity to radiotherapy. One of the most resistant factors to radiation is that tumor cells arecommonly hypoxic. The study on radiosensitizing agents is one of the most interesting issues intumor radiotherapeutics. These radiosensitizing agents can be classified into three main categories:natural products, synthesized chemicals and gene therapeutic agents according to their origins andtherapeutic techniques. Many radiosensitizing agents have some side-effects when they are active;so, it is important and significant to do our best to find more radiosensitizing agents with higherefficiency and lower side-effects. On the other hand, the tumor cells are easy to become resistantto older radiosensitizing agents; hence, it is urgent to develop newer radiosensitizing agents forclinics. Natural products come from plants, animals and other living beings. When serving asradiosensitizing agents in tumor radiotherapy, they are more attractive and predominant than generaldrugs. The reasons include a great resource ( especially in China) , multifunctional regulation,higher effectiveness and safer clinical effects.
