Breast Cancer Breast cancer is abnormal cell growth in a person's breast tissue. When you have reached an advanced stage, removal of the breast is sometimes performed for patient safety. This is certainly a scary thing for a woman. Almost all cancers have a specific cause. For example, most cases of skin cancer caused by ultraviolet rays of the sun. While lung cancer caused by smoking. But there is no single definitive cause for breast cancer. Several factors could be the cause of breast cancer. For example, genetic, environmental, and hormones may contribute to the breast cancer. Women are vulnerable to these factors may have a higher risk.