Pyrrolitinib has the efficacy of inhibiting the growth of sleeping tumor cells and can be used to treat recurrent or metastatic breast cancer that is epidermal growth factor receptor 2 positive and has not previously received or received trastuzumab, but the patient needs to have received anthracycline or paclitaxel-based chemotherapy prior to treatment with this drug. Pyrrolitinib is a small molecule receptor complex kinase inhibitor drug, can inhibit inhibit HER2 high expression of breast cancer cells, ovarian cancer cells, gastric cancer cells. The drug is clinically used in combination with capecitabine for the treatment of recurrent or metastatic breast cancer, but patients need to have received anthracycline or paclitaxel chemotherapy before receiving this drug. ADVERSE REACTIONS: The most common adverse reactions to this drug in combination with capecitabine in the treatment of breast cancer include gastrointestinal reactions, skin reactions, hepatobiliary disorders, metabolic and nutritional disorders, and hematologic disorders. Contraindications: the drug must be contraindicated in people who are known to be allergic to any of the components contained in the drug. Precautions: Diarrhea is the most common adverse reaction caused by the drug, which can be dealt with by symptomatic treatment, suspension of the drug or reduction of the drug dose. Discontinue treatment if severe hepatic abnormalities occur during administration. Pyrrolitinib should be applied under the guidance of physicians with antitumor experience, individuals should not abuse the drug on their own, and serious adverse reactions during the use of the drug should be promptly notified to the physician for disposal.