How can you actually die from breast cancer?

Cancer spreading: Breast cancer, just like most other solid cancers, causes death mainly through the dissemination of cancer cells to other organs such as brain, lungs, liver, bones, ect, in a process called metastasis. Some people died peacefully. Some people died after experiencing a lot of symptoms such as shortness of breath (from cancer in lungs or pleural effusion or pericardial effusion) or bone pain.