Tennis legend Martina Navratilova announced that she has breast cancer, on Good Morning America on Wednesday. Navratilova called the day of her diagnosis a "personal 9/11" that "devastated" her. After a routine mammogram, Navratilova was diagnosed with aggressive ductal carcinoma in situ, the earliest form of breast cancer. A lumpectomy determined that the cancer hadn't spread to her lymph nodes, which suggests that "I'm OK and I'll make a full recovery," she said. Navratilova spoke out because she wants to encourage other women to have mammograms.