Breast cancer is formed in the breast cells. I his cancer can affect both men and women, but most commonly it occurs in women. It is an abnormal growth of the cells lining the breast lobules or ducts which can have an uncontrollable growth and has the potential to spread to other parts of the body. When the breast cancer cells move to other parts of the body through the blood or lymph vessels it is called a metastasis which can spread further through the body to areas such as bones, brain, liver and lungs.