Diffusing Alpha-emitters Radiation Therapy-A New Approach for Solid Cancer Treatment

Alpha particle irradiation is known to be lethal to cancer cells. However, there is currently no treatment that effectively utilizes alpha particles against solid tumors. We propose a new approach - Diffusing Alpha-emitters Radiation Therapy - that, based on results obtained on murine models, holds great promise for the treatment of human solid cancer. The basic idea is to insert into the tumor a source, or a number of sources, bearing alpha emitting atoms closely below their surface. As these atoms disintegrate, their daughters, which are short-lived alpha emitters themselves, recoil into the tumor, spread through its volume and decay at therapeutically significant distances. Each source generates a 'killing zone' whose size is determined both by the tumor vasculature and by the half-lives of the diffusing atoms. We implement this scheme using 228Th to generate sources bearing 224Ra, which, once inside the tumor, release by recoil 220Rn, 216Po and 212Pb atoms into the tissue. In the article, we discuss the basic principles involved and demonstrate the effect of such sources on murine Squamous Cell Carcinoma tumors