The Princess of Wales has revealed she is being treated for cancer.In a video statement released by Kensington Palace, she said the presence of cancer was discovered after she underwent major abdominal surgery in January.The surgery was successful and it was thought at the time her condition was non-cancerous.However, post-operative tests subsequently found that cancer had been present.Neither Kensington Palace nor Kate has confirmed the type of cancer that was discovered.She began a course of preventative chemotherapy in late February and is understood to be on a recovery pathway,