Breast cancer is caused by malignant cells developing in breast tissue. It is the most commonly diagnosed cancer in women, but advancements in treatment options have seen the death rate decline since the 1990s. Common warning signs of breast cancer include lumps, changes in breast size or shape, discoloration, dimpling of the skin, new concentrated pain in the breast, and rash on the nipple. Yearly mammograms and self-exams are an important part of early detection of breast cancer.
