Nanoparticle-Enabled Immune-Dose Shaping in Breast Cancer Radiotherapy: Reconciling Tumor Immunogenicity with Systemic Immune Preservation.

Radiotherapy can simultaneously promote tumor immunogenicity and damage the systemic immune compartments required to sustain antitumor responses. In breast cancer, radiation-induced lymphopenia is influenced by treatment geometry, irradiated volume, low-dose exposure, marrow and lymphoid irradiation, fractionation, and delivery characteristics, while nanoparticle radioenhancement can amplify tumor response through physical, redox, DNA-repair, and immune mechanisms. This hypothesis-driven translational review examines whether nanoparticle-generated biological amplification could be redirected from tumor intensification toward immune-dose shaping while preserving tumor control and immunogenicity. The evidence supports seven interacting dimensions of potential exchange: physical dose, volume/spatial exposure, distributed low-dose exposure, marrow dose, geometry/modality, fractionation, and temporal/delivery exposure. Formal nanoparticle-enabled dose exchange remains limited, with the clearest breast-specific evidence confined to in vitro isoeffect analysis; no study has yet demonstrated preserved tumor isoeffect and immunogenicity together with reduced multicompartment immune injury after nanoparticle-enabled exposure reduction. We, therefore, propose a dual-endpoint framework integrating tumor control, immunogenicity, multicompartment immune preservation, dosimetry, and nanoparticle biodistribution, together with a staged translational pathway from quantitative preclinical exchange studies to comparative clinical testing. This strategy remains hypothesis-generating, with triple-negative breast cancer representing a particularly informative initial setting.