T-DXd produced 1.869, 1.994, and 1.684 QALYs (3.275, 3.484, and 2.988 LYs) and chemotherapy gained 1.326, 1.436, and 0.895 QALYs (2.393, 2.598, and 1.626 LYs) for overall, HR+, and HR- HER2-low ABC patients, respectively. This evidence concerns the gene ERBB2 and aneurysmal bone cyst.