The purpose of this study is to evaluate the efficacy and safety of high-intensity focused ultrasound (HIFU) combined with toripalimab plus chemotherapy versus chemotherapy as neoadjuvant therapy for ER+/HER2- breast cancer.

Study participants will be randomly allocated to either the experimental group or the control group and receive the following treatments. Experimental group: HIFU therapy followed by 8 cycles of neoadjuvant immunotherapy and chemotherapy; Control group: 8 cycles of neoadjuvant chemotherapy alone. Each cycle lasts 21 days. Subsequently, all participants will undergo surgery within 6 weeks after completion of neoadjuvant therapy.

Inclusion Criteria:

1. Female patients aged 18-75 years.
2. Invasive breast cancer without distant metastasis, including either T1c-T2 (≥ 2 cm), cN1-cN2, or T3-T4, cN0-cN2.
3. Histopathologically confirmed ER-positive/HER2-negative, PR < 20% or Ki67 ≥ 20%, Grade 3 breast cancer.
4. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.

Exclusion Criteria:

1. Female patients during pregnancy or lactation.
2. Diagnosis of bilateral breast cancer, occult breast cancer, or distant metastasis confirmed by pathology.
3. Has an active autoimmune disease that has received systemic treatment in the last 2 years.
4. Has a known history of human immunodeficiency virus (HIV), hepatitis B, or known active hepatitis C virus infection.
5. Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent.
6. Has a known history of invasive malignancy that required systemic treatment in the last 5 years.
7. Uncontrolled concomitant diseases include severe infection, liver disease, cardiovascular disease, kidney disease, respiratory disease, diabetes, and others requiring systemic treatment.