Kate, the Princess of Wales, has disclosed that she has cancer but hasn’t said what kind. In a video announcement Friday, she revealed that she was undergoing chemotherapy but didn’t give further details of her treatment. Kate had successful abdominal surgery in January. At the time, officials said her condition wasn’t cancerous. But Kate says tests done later found the cancer. Kensington Palace said that no details about her cancer or her treatment would be released, saying she has a right to medical privacy. After successful surgery, chemotherapy is often used to help kill any stray cancer cells and to prevent the cancer from coming back.