Chemotherapy combined with trastuzumab and patuzumab is the standard neoadjuvant therapy for HER2 positive breast cancer patients. The survival rate of patients with pathological complete response (PCR) after neoadjuvant therapy was significantly better than that of patients with tumor residue, that is, non-PCR. Therefore, studies have confirmed that adjuvant therapy for patients with non-PCR after neoadjuvant chemotherapy can further improve the prognosis and survival of this population. However, the results of previous studies are based on trastuzumab target therapy in neoadjuvant therapy. Therefore, there are different recommendations for the current guidelines of adjuvant therapy after trastuzumab combined pertuzumab target neoadjuvant therapy. Patients with HER2 positive breast cancer who received trastuzumab and patuzumab based neoadjuvant therapy had invasive residual cancer in postoperative pathology. The effect of postoperative adjuvant therapy with trastuzumab and patuzumab or replacement of T-DM1 on survival.

Investigators retrospectively recruited patients with HER2 positive breast cancer who received trastuzumab and patuzumab based neoadjuvant therapy had invasive residual cancer in postoperative pathology from January 1, 2019 to November 31, 2024, and prospectively recruit patients of the same type from December 1, 2024 to December 31, 2028.

Inclusion Criteria:

1. Patients with HER2 positive breast cancer were diagnosed by biopsy in Peking University People's hospital;
2. The clinical stages before treatment were T1-T4, N0-N3, M0;
3. Received treatment and operation in our hospital, and had hospitalization records;
4. Receive at least 4 cycles of trastuzumab and pertuzumab target therapy combined chemotherapy as neoadjuvant therapy
5. Postoperative pathology confirmed the presence of residual invasive breast cancer in the breast and/or metastatic tumor lesions in axillary lymph nodes;
6. Has signed and agreed to participate in the PKUPH breast disease cohort study.

Exclusion Criteria:

1. Lack of clinical and pathological data (such as imaging data and pathological data);
2. Patients with metastatic breast cancer or bilateral breast cancer;
3. Failure to perform radical surgery;
4. Receiving other regimens besides the established neoadjuvant regimens.

The therapy choice Arm 1: The postoperative adjuvant regimen is a combination of trastuzumab and pertuzumab, with a planned treatment duration of 1 year; Arm 2: Postoperative adjuvant therapy was T-DM1, with a planned treatment duration of 1 year.

Primary end point 3-years invasive disease free survival

Inclusion Criteria:

• 1) Patients with HER2 positive breast cancer were diagnosed by biopsy in Peking University People's hospital;
• 2) The clinical stages before treatment were T1-T4, N0-N3, M0;
• 3) Received treatment and operation in our hospital, and had hospitalization records;
• 4) Receive at least 4 cycles of trastuzumab and pertuzumab target therapy combined chemotherapy as neoadjuvant therapy
• 5) Postoperative pathology confirmed the presence of residual invasive breast cancer in the breast and/or metastatic tumor lesions in axillary lymph nodes;
• 6) Has signed and agreed to participate in the PKUPH breast disease cohort study.

Exclusion Criteria:

• 1) Lack of clinical and pathological data (such as imaging data and pathological data);
• 2) Patients with metastatic breast cancer or bilateral breast cancer;
• 3) Failure to perform radical surgery;
• 4) Receiving other regimens besides the established neoadjuvant regimens.

HER2 positive breast cancer patients with residual invasive breast cancer after neoadjuvant chemotherapy combined with trastuzumab and pertuzumab