Trastuzumab is effective when you stop for a few months and then pick up the shot. Trastuzumab is also a targeted drug that is mainly used for the treatment of metastatic breast cancer caused by HER2 gene overexpression, metastatic gastric cancer, and adjuvant chemotherapy for breast cancer. Early stage breast cancer patients use trastuzumab for one year after surgery to prevent breast cancer recurrence. If breast cancer recurrence or metastasis occurs after surgery, trastuzumab can be used to treat breast cancer, and the duration of use can be determined according to the degree of tumor progression and metastasis, and the dosage of trastuzumab can be adjusted according to the actual situation. Trastuzumab is an effective drug for the treatment of breast cancer, and should be administered according to the doctor’s instructions, while Trastuzumab may cause fever, diarrhea and other adverse reactions, and if the physical condition is abnormal, it can be examined in the hospital.