Eradicating Cancer Stem Cells Using High Linear Energy Transfer Radiation Therapy Part 1: Physics and Radiobiology

Linear energy transfer (LET), a measurement of ionization density, tracks the radiobiological potency of any given course of therapeutic radiation and its efficacy in killing cancer cells. As opposed to the low LET of photon and proton therapy, high LET charged particle therapy can overcome multiple mechanisms of resistance to effectively treat radioresistant tumors. In part 1 of this two-part series, we review the physics and radiobiology of high LET to demonstrate its unique capability to address the problem of cancer stem cells (CSCs), which remain largely impervious to conventional therapies and are the ultimate explanation of progression and metastasis as well as the dire prognosis of malignancies such as pancreatic cancer and glioblastoma at any stage.