Breast cancer is a disease caused by malignant cells that grow in breast tissue. It is the second leading cause of death for women globally. Risk factors include family history, early menstruation, and age over 40. Symptoms include painless breast lumps, nipple discharge or changes to the breast skin or shape. Diagnosis involves clinical exams, mammograms, ultrasounds and sometimes MRI. Breast cancer stages range from Stage I (small tumor), to Stage IV (cancer has spread to distant organs). Steps to prevent breast cancer include avoiding alcohol, eating fruits and vegetables, and exercising regularly.