ALPHA-EMITTING AND BETA-EMITTING RADIOLANTHANIDES IN TARGETED CANCER THERAPY - THE POTENTIAL ROLE OF TERBIUM-149

The efficacy of systemic cancer therapy rests on the ability of a toxi n to be preferentially located in cancer cells, so that cancer cell ki ll is maximized and normal tissue spared. This requires that the lifet ime of the toxin be less than the lifetime of the carrier in the body, effectively ruling out chemical toxins, as they remain effective unti l excreted from the body. The requirement of localization of dose to t he cancer cell makes radioactive beta-emitting radionuclides unattract ive. Alpha-emitting radionuclides are much more appropriate toxins, as their efficacy depends on the high energy and short range of the alph a particles, and terbium-149 is shown to be the most efficacious of th ese. However, the merit of various alpha- and beta-emitting radionucli des depends on the stage and type of cancer. Recommendations are made with respect to the matching of the target cancer with required proper ties of the radiolabel and carrier.