Pre-operative Radiation and Immunotherapy in the Treatment of Non-metastatic Breast Cancer

Purpose of Review: To discuss the rationale and latest strategies for combining pre-operative radiation therapy (pre-op RT) and immunotherapy (IO) in the treatment of non-metastatic breast cancer. Recent Findings: IO has recently been incorporated into the standard-of-care treatment for patients with stage II–III triple-negative breast cancer. Other subtypes of breast cancer have notably been excluded from most major IO trials due to their perceived lack of immunogenicity, though oncologic outcomes for all high-risk patients warrant further improvement. Early-phase clinical trials have demonstrated the feasibility of pre-op RT. There is a sound pre-clinical basis for the combination of pre-op RT and IO to induce robust local and systemic anti-tumor immunomodulation in patients with all types of breast cancer. Summary: There is emerging interest in utilizing pre-op RT to prime the anti-tumor immune response and potentially promote an abscopal effect when combined with IO. Trials investigating various combinations of pre-op RT and IO are underway.