ANNOUNCER: But now science has developed an even more targeted form of radiation through a treatment called radioimmunotherapy. NHL is the first type of cancer to be treated with this therapy, using a medicine called Zevalin. In radioimmunotherapy, radiation is linked to antibodies. Typically your immune system uses antibodies to circulate through the bloodstream and attack foreign substances. Like a medical missile, these radioactive antibodies head through the bloodstream to the tumor areas where they attach to cancer cells and destroy them.
LEO GORDON, MD: Radioimmunotherapy takes advantage of the fact that we already have antibodies, which we can target to malignant cells. Radioimmunotherapy adds to that by attaching radioactive particles or radioactive substances to that antibody.
ANNOUNCER: While both external beam therapy and radioimmunotherapy treatments are powerful tools, the nature of the illness will dictate which is the best weapon.
LEO GORDON, MD: If you've got a single large mass that's causing obstruction or symptoms, I think that's a nice role for external beam radiation. If you have multiple masses, multiple tumors, you can't treat them all with external beam radiation. That would be a circumstance where I think radioimmunotherapy would be most effective.
ANNOUNCER: These two therapies differ in the kinds of radiation they use.
ELI GLADSTEIN, MD: External beam therapy refers to a machine that produces radiation. It produces x-rays of very high energy such that they can penetrate tissue.
LEO GORDON, MD: Radioimmunotherapy, the radionuclide has sort of built-in properties where they're either what we call, gamma radiation, such as radioactive iodine, or beta radiation, such as yttrium-90.
ANNOUNCER: Conventional radiation therapy is delivered with an external beam over an extended time, while the radiation in radioimmunotherapy is delivered through the vein over a much shorter time.
