Researchers and medical engineers are taking the building blocks provided by modern biotechnology and assembling impressive technology demonstrations of effective cancer therapies. VOA News reports on one of the latest: "We put radio-labeled antibodies that we know bind to breast cancer on the nanoparticles' surface, and then injected them into mice in which we had implanted a very aggressive human breast cancer. ... The antibody-nanoparticle combinations attached themselves to the breast cancer tumor cells. Then the researchers applied an external 'alternating magnetic field' (AMF) to the area around the tumors [causing] the iron nanoparticles to become very hot. The heat then kills the breast cancer cells without harming the healthy tissue around the tumor. ... If we give, in 20 minutes, a certain dose of the alternating magnetic field into the tumor area, we know the dose of heat we should have created on the tumor. .. The tumors basically responded, some of them going away, some of them slowing in their growth rate, and that correlated closely with the calculated heat dose."