Breast cancer begins when breast cells become uncontrollable. These cells usually form a tumor that is often seen on an x-ray, or you can feel a mass. The tumor is malignant (cancer) cells can grow when the tissue (penetrating) or spread (metastases) surrounds in the distant area of the body. Breast cancer occurs almost exclusively in women, but men can also get breast cancer. The cells of almost all parts of the body can become…"What Is Breast Cancer?"