NEW YORK — Actress Helen Wagner, who played mild-mannered Nancy Hughes on the CBS soap opera “As the World Turns” for more than a half-century and spoke its first words, has died at age 91. She died Saturday, said the show’s New York-based production company, TeleNext Media Inc., which didn’t say where she died or what was the cause of her death. Wagner opened “As the World Turns” when it premiered on April 2, 1956.