Breast cancer is the most common malignancy in women worldwide. Patients with breast cancer are often diagnosed at later stages and have a strong desire for breast conservation, necessitating neoadjuvant chemotherapy. Tumors of different molecular subtypes and individual variations among patients lead to significant differences in treatment efficacy. Precise assessment of patients' responses to treatment regimens is imperative in advancing prognosis of breast cancer. In this study, 58 patients diagnosed with breast cancer and scheduled for neoadjuvant therapy will be recruited. Patient-derived organoids from their tumor biopsies will be utilized to evaluate the sensitivity of chemotherapy regimen. These drugs primarily include Doxorubicin, Carboplatin, Cyclophosphamide, Paclitaxel, as well as targeted therapies such as Herceptin and Pertuzumab.

58 early-stage breast cancer patients scheduled to undergo neoadjuvant therapy will be recruited. Baseline information including medical history, ultrasound, Breast-Specific Gamma Imaging (BSGI), and magnetic resonance imaging (MRI) records, will be collected both before and after two cycles of chemotherapy. Tumor tissue from these patients will be obtained via biopsies guided by ultrasound. Patient-derived organoids (PDOs) will be established and cultured from the collected tumor tissue. Subsequently, these PDOs will be subjected to treatment with drugs from standard chemotherapeutic regimens for breast cancer. The growth of the organoids will be assessed post-treatment, and dose-response curves will be generated. For evaluating the clinical outcomes of the patients, the Residual Cancer Burden (RCB) system will be used to evaluate tumor histological responses in patients. The consistency between treatment responses observed in the PDO models and the clinical outcomes of patients will be evaluated through correlation analysis.

Inclusion Criteria:

1. Signed informed consent form and willingness to participate in the clinical study.

2. Female patients aged between 18 and 70 years old.

3. Confirmed early-stage breast cancer eligible for surgery (AJCC stages I to IIIA), with a tumor diameter of ≥ 2cm detected by MRI and without distant metastasis (M0).

   The largest lesion among multiple lesions has a diameter of ≥ 2cm.

4. ECOG performance status score of 0-1.

5. No significant abnormalities in liver and kidney function (BIL <1.5-fold upper limit of normal (ULN)；ALT<2.5×ULN; AST<2.5×ULN；Crea≤1×ULN).

Exclusion Criteria:

1. Received prior treatments.
2. Locally advanced breast cancer not amenable to surgery or inflammatory breast cancer (AJCC stage unresectable III).
3. Bilateral breast cancer.
4. Multiple breast cancers distributed in different quadrants.
5. Patients not suitable for neoadjuvant chemotherapy.

Male breast cancer is a rare disease.

Patients with breast cancer (AJCC stages I to IIIA) who need to receive neoadjuvant therapy.