Last year, more than 232,000 women were told they had invasive breast cancer — in which cancer cells have spread beyond the mammary glands — and another 64,000 were diagnosed with in situ breast cancer, in which the cancer is localized to the cells lining the breast ducts.
After cancers of the skin, breast cancer is the most common cancer among American women, accounting for almost a third of all newly diagnosed cases. It is also among the most deadly of cancers. Each year, approximately 40,000 women die from breast cancer. Only lung cancer kills more.