Breast cancer is the most common malignant tumor in women worldwide and neoadjuvant therapy has been the standard care for local advanced breast cancer. Moreover, neoadjuvant therapy undoubtedly provides an ideal model to evaluate the response to therapy. Cell-in-cell structures (CICs) refer to the presence of one or more cells inside host cell, which generally leads to the death of inner cells. Notably, established evidences indicated that CICs were present in breast cancer and tend to impact patient survival. However, whether CICs profile could predict efficacy of therapy remains unclear. In this prospective cohort study, the CICs number and profile will be detected in tumor tissue before and after the neoadjuvant therapy. Then the association between CICs number including dynamic changing and response rate will be explored.

Inclusion Criteria:

• Age 18-65, female;
• Pathological biopsy confirmed invasive ductal carcinoma;
• Karnofsky Performance Status (KPS)≥ 60, expected survival ≥4 months;
• Locally advanced breast cancer (HER2-positive disease and TNBC, ≥cT1c or ≥cN0； HER2-negative，HR positive disease，≥cT2 or ≥cN1；Large primary tumor relative to breast size in a patient who desires breast conservation) ;
• According to the RECIST1.1 standard, at least one measurable lesion exists;

Exclusion Criteria:

• Pregnant or lactating women;
• Left ventricular ejection fraction less than 50%;
• History of malignant tumor and concurrent occurrence of other tumors;
• Serious medical pathology, such as congestive heart failure; unstable angina; uncontrolled high risk arrhythmias, and other serious illness or medical condition that may interfere with the study;
• Refuse to participate in the study.

Patients with breast cancer treated with neoadjuvant therapy attending Beijing Shijitan Hospital from 2021-2023.