The cluster 2 comprised a total of 68 keywords, encompassing breast cancer, trastuzumab, HER2, chemotherapy, survival, pertuzumab, lapatinib, phase-II trial, open-label, efficacy, and etc. This cluster primarily focused on investigating the safety and efficacy of breast cancer chemotherapy as well as targeted HER-2 therapies through clinical trials. This evidence concerns the gene ERBB2 and breast cancer.