JEDDAH, 25 April — Crown Prince Abdullah, deputy premier and commander of the National Guard, will attend the opening of a tumor center at the King Abdul Aziz Medical City in Jeddah today. Prince Abdullah will also lay the foundation stone for a guest house for tumor patients in the city. The center will receive patients from all parts of the Kingdom, said Fahd ibn Abdullah Abdul Jabbar, executive director of health affairs at the National Guard, yesterday.