Abstract: Objective To investigate the expression of lung resistance protein(LRP) genes in breast cancer and to explore the role of multi-drug resistance mechanism in breast cancer and its clinical significance. Methods Totally 81 female cases of breast cancer, who were treated in the department of general surgery of Beijing Friendship Hospital in 2000, aged 30~83 years (average 53.2 years), accepted the comprehensive treatment with surgery without neoadjuvant chemotherapy. Pathological types included invasive ductal carcinoma, invasive lobular carcinoma, the only cancer, mucus cancer and early invasive cancer. According to standards of International Union Against Cancer(UICC) 2003 version for clinicopathological staging of breast cancer, 17 cases were at stage Ⅰ, 43 cases stage Ⅱ, and 21 cases stage Ⅲ. Thirty-six cases had five-year follow-up results, 30 cases had disease-free survival for 5 years, 6 cases had metastasis(1 case survived with tumor and 5 cases died). Tissue chips were prepared. LRP expression in breast cancer tissue was determined by using immunohistochemistry and in situ hybridization, and other detection technology. Results According to manual reagents criteria of Maixin company, the results were separated into negative(-/+) and positive(++/+++). The positive rate of LRP in breast cancer was 70.4%(57/81). The 81 cases were divided into two groups: young and middle-aged group(age<50 years, 36 cases) and elderly group(≥50 years, 45 cases). It was found that positive correlation was not only found between LRP and ER but also between LRP and PR. The correlation coefficient were 0.327, 0.264, P＜0.05. But there was no correlation between LRP and p53, Her-2 and Ki-67, P> 0.05. Conclusion The expression of LRP increased in breast cancer evidently, there was correlation between the LRP expression and age, expression of ER and PR, which may provide basis for selecting the drug of chemotherapy.

Key words: breast cancer, multidrug resistance, lung resistance protein