Abstract: Objective To explore the expression of ribonucleotide reductase subuint M1(RRM1) and its relation to drug-sensitivity and the therapeutic effect of GP(Gemcitabine and Cisplatin) in advanced non-small cell lung cancer(NSCLC) .Methods RRM1 expression was tested immunohistochemically on 30 cases ofⅢ_b orⅣstage NSCLC treated with GP.The relationship between RRM1 expression and the chemotherapeutic effect was analyzed.Results The differences of RRM1 expression between the comparable factors such as sex,age,tumor size,pathological type and TNM phase were not statistically significant (P>0.05).The effect rates of GP treatment in RRM1-positive group and RRM1-negative group were 12.5%and 78.5% respectively and the 1-year survival rates in these two groups were 6.3%and 64.3%respectively,the differences were statistically significant(P<0.05 ).Conclusions There are negative relativity between the level of RRM1 expression and chemotherapeutic effect of GP in NSCLC.Chemotherapeutic effect of GP would be predicted by testing level of RRM1 expression in advanced NSCLC,and the level of RRM1 expression would be helpful for selecting individualized chemotherapeutic program.

Key words: Advanced non-small cell lung cancer, Immunohistochemistry, RRM1, Individualized chemotherapy