The generic name of Herceptin is trastuzumab, and there is no authoritative literature indicating that the drug can be used for cancer prevention. The drug is mainly used for targeted treatment of some breast cancers, and contraindications should be noted. Trastuzumab is a targeted drug for the treatment of HER2-positive breast cancer, which requires the presence of a clear therapeutic target to be effective. There is no evidence of cancer prevention with this drug. Serious adverse effects such as thrombocytopenia and peripheral neuropathy are associated with the use of this drug, which requires close supervision and is contraindicated in normal subjects. For breast cancer patients, if there is no relevant target, or the existence of drug allergies and other conditions also prohibit the use of the drug. In daily life, it is recommended to have a regular work and rest schedule, reasonable diet, avoid smoking and drinking, which can reduce the probability of disease; adhere to the regular physical examination, which can be early detection of undesirable foci and early intervention. Trastuzumab needs to be used under the guidance of clinicians, and unauthorized use of the drug is prohibited.