Breast cancer
The breast is a gland designed to make milk. The lobules in the breast make the milk, which then drains through the ducts to the nipple.
Like all parts of your body, the cells in your breasts usually grow and then rest in cycles. The periods of growth and rest in each cell are controlled by genes in the cell’s nucleus. The nucleus is like the control room of each cell. When your genes are in good working order, they keep cell growth under control. But when your genes develop an abnormality, they sometimes lose their ability to control the cycle of cell growth and rest.