Invasive breast cancer that has grown 4mm in a month needs to be treated with surgery, continuation of the current treatment program, or a change in the treatment program, depending on the situation. 1. Surgery: If invasive breast cancer has grown 4mm in a month, if CR (complete remission) is achieved and the current neoadjuvant treatment course is sufficient, surgery can be considered to remove the tumor tissue. However, if the course of treatment has not yet been completed, you can choose to have surgery first, and then make up the full course of treatment or continue to complete the course of treatment and then have surgery. It is recommended to follow the clinician’s advice. 2. Continue with current treatment: If invasive breast cancer grows 4mm in a month and is evaluated as PR (partial remission), it is considered that the current treatment plan can be continued. 3. Change of treatment plan: If invasive breast cancer has grown 4mm in a month, if the evaluation of the efficacy of the treatment is SD (stable disease) or PD (disease progression), then a change of treatment plan should be considered, and should follow the advice of the clinician. If invasive breast cancer has grown 4mm in a month, it is important to seek medical attention and receive treatment as prescribed. Do not stop medication without authorization, etc., to avoid delays.