The goal of this clinical trial is to compare the efficacy and safety in patients with lymph node-positive HR+/HER2- breast cancer. The main questions it aims to answer are:
* Can the incorporation of intensified radiation to the tumor (tumor boost) enhance the pCR rate on the basis of neoadjuvant immuno-chemotherapy？ * Can it improve the level of residual cancer burden (RCB) and change the tumor immune microenvironment? and How safe will be the combined therapy?
Participants will be randomly assigned to one of three treatment regimens:
1. Preoperative toripalimab combined with SBRT targeting both the primary tumor and axillary lymph nodes, followed by chemotherapy; 2. Preoperative toripalimab combined with SBRT focused solely on the primary tumor, followed by chemotherapy; 3. Preoperative toripalimab combined with chemotherapy alone.
Following the completion of their respective treatment regimens, participants will proceed to undergo surgery. The effectiveness of the treatments will be assessed through pathological evaluations, as well as by measuring levels of residual cancer burden (RCB) and examining changes in the tumor immune microenvironment.
The study aims to evaluate the safety of these combined treatment approaches and to determine if they offer superior efficacy compared to outcomes reported in previous studies.
High-risk HR+/HER2-negative breast cancer is defined as ER≥1%, HER2-negative (<2+ Her2 IHC or <2.2 HER2/CEP17 ratio by FISH) and either histologic grade II-III or a high-risk genomic assay score (Oncotype RS>25, high risk Mammaprint, PAM-50, EndoPredict or ProSigna score). primary tumor size ≥1.0 cm in maximum diameter and axillary node-positive breast cancer;
Stage T1-4N+M0 (i.e., Stage II, III), with confirmed N+ by biopsy, and no signs of distant metastasis;
The initial PD-L1 expression level conducted on the tumor tissue sample with Combined Positive Score (CPS) or Tumor Proportion Score (TPS)< 10%;
ECOG score of 0-1;
Inflammatory breast cancer
Life-threatening organ dysfunction or complications, active infectious diseases, active hepatitis B, hepatitis C virus infection, autoimmune diseases within two years, undergoing immunosuppressive drug treatment or chronic systemic corticosteroid therapy (dose exceeding 10mg per day of prednisone or equivalent);
Clinically symptomatic heart disease;
Previous systemic treatment or radiotherapy for breast cancer;