Objective:To investigate radiosensitization and mechanism of Chinese medicine Jiawei Shengmai San on nasopharyngeal carcinoma. Method: The SD rats swimed in Glass tank for 10 minute in 30 days

at the same time

subcutaneous injection of dinitrosopiperazine(DNP) was performed

the dose was 0.5 mg every time

every 3 days the injection was carried out once for 90 days. Then

nasopharyngeal carcinoma models with Qi deficient status was produced.The samples were divided into control group

drug group

radiotherapy group

drug+radiotherapy group.The radiosensitization effect was measured by measuring tumor volume and weight

and multidrug resistance 1 gene(MDR1) expression was detected by quantitative PCR and western-blot. Result: In the control group tumor weight was (1 230.0±106.8) mg

in the radiotherapy group being (447.2±121.9) mg. Compared with the control group

the ratio of tumor inhibition was 53.25%

there was a significant difference (P<0.05). In the drug+radiotherapy group tumor weight was (259.9±64.7) mg

the ratio of tumor inhibition was 72.81%

there also was a significant difference (P<0.05). The Relative expression ratio

in the drug group was 1.21

the radiotherapy group was 1.85

drug+radiotherapy group was 1.34. Conclusion: Jiawei Shengmai San can enhance the sensitivity of radiotherapy to the nasopharyngeal carcinoma

and its mechanisms may be related to regulating MDR1 gene expression.