Tumor Blood Vessels Targeted with Radioisotopes in Cancer Therapy

  Therapy of metasteses from solid tumors remains as a major problem in curing carcinoma-the major cause of death from cancer in humans. Much current work has focused on tumor blood vessels as a target for directed therapy. Inhibition of the growth of new blood vessels has shown to keep tumors at bay, but does not actually cure the cancer. Working in a mouse model system, scientists in the ORNL, Life Sciences Division have used radioisotopes targeted to tumor blood vessels to kill not only the cells lining the vessels, but also the tumor cells they serve. In the most recent experiments, the effects of an alpha-particle emitter, 21 3Bi, and a beta-particle emitter 90Y were compared. Alpha particles can travel only about 10 cell thicknesses in tissues but are extremely destructive in their short path length, whereas beta particles can travel 100 times farther, but are less destructive per unit path length.

 The data show that mice bearing artificial metasteses in their lungs can be cured of the tumors with vascular targeting of either radioisotope; however, the beta-particle emitter causes more damage to the adjacent normal lung as well as nearby organs. These results indicate that for radioimmunotherapy by vascular targeting to small tumors, up to 2000 cells or so the "surgical strike" of a vessel targeted alpha-particle emitter is a more focused and specific agent for therapy.

Contact: Steve Kennel, 574-0825 or sj9
Phone: (423)574-0825
E-mail: sj9@ornl.gov