A study by the UPenn group reported that FLASH proton radiotherapy (F-PRT) of the C57BL/6 murine hind leg produced fewer severe toxicities leading to death or requiring euthanasia than standard proton therapy (S-PRT) of the same dose.

RNAseq analyses of murine skin and bone revealed pathways upregulated by S-PRT yet unaltered by F-PRT. F-PRT reduced skin injury, stem cell depletion, and inflammation, mitigated late effects including lymphedema, and decreased histopathologically detected myofiber atrophy, bone resorption, hair follicle atrophy, and epidermal hyperplasia. F-PRT was equipotent to S-PRT in control of two murine sarcoma models.