Impact of chronic low-dose external gamma- and internal tritium beta-irradiation on the gut microbiome in the context of intestinal tumorigenesis in <i> Apc ^Min/+ </i> mice

Low-dose ionizing radiation is one of the few environmental stressors that simultaneously reshapes host physiology and the structure-function landscape of resident microbiomes, yet mechanistic insight at ecologically relevant doses has been scarce. By integrating longitudinal 16S rRNA profiling, multiplex cytokine analyses, and quantitative tumor phenotyping in the <i>Apc</i>^<i>Min/+</i> mouse model, our study demonstrates that continuous exposure to either external ⁶⁰Co γ-photons or tritium beta particles perturbs gut microbial community structure in radiation-quality-specific ways and that these shifts track with, and sometimes precede, complex, non-monotonic changes in intestinal tumor burden. The work expands the traditional radiobiology focus from host-centric DNA damage to a systems-level view in which microbe-host-radiation interactions form a dynamic network influencing early colorectal carcinogenesis.