Researchers at Harvard Medical School investigated how breast cancer arises. They found that breast cancer arises from “genomic reshuffling — rearrangement of chromosomes — that activates cancer genes and ignites disease.” They also found that the “sex hormone estrogen — thus far thought to be only a fuel for breast cancer growth — can directly cause tumor-driving genomic rearrangements.” Current treatments for breast cancer include surgery, radiation therapy, and chemotherapy, but new treatments such as immunotherapy and targeted therapy are also being developed. Researchers continue to investigate the genetic and molecular mechanisms underlying breast cancer in order to develop more effective treatments and preventative measures.