King Charles is being treated for a form of cancer, Buckingham Palace has announced.The shock news comes a week after the king was discharged from a private London hospital after a scheduled treatment for an enlarged prostate.At the time the Palace said that his condition was benign.He spent three nights at the London Clinic before being discharged last Monday.At the time, the Palace said the monarch had "rescheduled forthcoming public engagements to allow for a period of private recuperation.”