DLL3 and breast cancer: Antibody-drug conjugate, HER2, breast cancer, T-DM1, target therapy, ovarian cancer, and small cell lung cancer are at intermediate, while gastric cancer, triple-negative breast cancer, bladder cancer, urothelial carcinoma, nectin-4, dll3, sacituzumab govitecan, and trastuzumab deruxtecan are novel topics.