Letrozole是一非甾体芳香酶抑制剂,较氨基导眠能(AG)有较高的抗肿瘤活性和更高的特异性。在荷瘤小鼠DMBA诱发乳癌动物模型中,Letrozole可完全抑制肿瘤生长,活体标本上几乎完全消退。人体实验中,给予剂量从0.02～3mg,血浆雌二醇(E1)、雌三醇(E2)水平随剂量增加而逐降,达基础值的80％～90％, Letrozole is a non-steroidal aromatase inhibitor that has higher anti-tumor activity and higher specificity than Amino-lipid (AG). In animal models of DMBA-induced breast cancer in tumor-bearing mice, Letrozole completely inhibited tumor growth and almost completely resolved on living specimens. In human experiments, the dose was from 0.02 to 3 mg, and plasma estradiol (E1) and estriol (E2) levels decreased gradually with increasing doses, reaching 80% to 90% of the baseline value.