In recent years, small-molecule tyrosine kinase inhibitors (TKI) have achieved good results in anti-HER2 therapy and have been widely used in clinical practice, such as Breast cancer. However, such drugs can easily cause diarrhea and disorders of intestinal flora , may affect the efficacy of the drug and lead to the occurrence of other diseases.This study is to clarify the connection between the diarrhea caused by pyrotinib and the change of intestinal flora, pave the way for studying on whether the flora affects the efficacy of the drug and whether the flora should be supplemented appropriately in the future.
