肿瘤是危害人类生存的主要疾病之一。以乳腺癌为例在美国每年新发生病例达到 182 ,0 0 0例 ,46,0 0 0人死于乳腺癌。患癌致死已成为第二位死亡原因[1] 。早期肿瘤在没有发生转移的情况下通过手术和局部放疗可以治愈。但是由于肿瘤早期诊断困难及易转移的特性 ,肿瘤患者经常是在 Cancer is one of the major diseases that endanger human survival. Take breast cancer as an example. In the United States, the number of new cases each year reaches 182,000, and 400,000 people die of breast cancer. Cancer death has become the second cause of death [1]. Early tumors can be cured by surgery and local radiotherapy without metastasis. However, due to the difficult diagnosis and early metastasis of tumors, tumor patients are often