Breast cancer originates in the breast tissue. Like other cancers, breast cancer can invade and grow into the tissue surrounding the breast. It can also travel to other parts of the body and form new tumors, a process called metastasis.
We do not know what causes breast cancer, although we do know that certain risk factors may put you at higher risk of developing it. A woman's age, genetic factors, family history, personal health history, and diet all contribute to breast cancer risk.