Breast cancer is a terrible, devastating disease that can affect anyone. It is the most common type of cancer that affects women (although it can also affect men). Clinical trials are extremely important scientific studies needed and required to assess new medical treatments, including treatments for diseases such as breast cancer. Learn more about how breast cancer can be diagnosed. According to the American Cancer Society, better treatment options are improving a patient’s chances of surviving breast cancer. Currently, the five-year relative survival rate for women who have either stage 0 or stage 1 breast cancer is close to 100%. Later-stage breast cancer has a lower survival rate, but it is still high: For women with stage 2 breast cancer, the five-year relative survival rate is about 93%, while for stage 3 breast cancers it is about 72%. In addition to helping patients by making the best possible treatments available, clinical trials also advance scientific understanding of a disease or disorder.