The 71-year-old underwent a 90-minute surgery on Tuesday at Rome's Gemelli Hospital and was subsequently diagnosed with lung adenocarcinoma - a type of cancer usually found in the outer part of the organ. "The operation was successful and there were no complications", the Vatican said. "After the operation, the Pope awoke normally and returned after a brief period of observation to his room." The pontiff had a "peaceful night" in the hospital, the Vatican said on Wednesday morning, and he is expected to remain there for about a week. Large crowds had waited outside the hospital for the Pope's arrival on Tuesday, cheering as he waved and smiled through a window as his car went past. He was met by staff on the hospital steps. "I'm sorry", one of them commiserated, to which the Pope gave a smile and a shrug. The Vatican said the whole lower lobe of the Pope's right lung was removed during a roughly 90-minute surgery "to ensure the procedure was radical". It was Leo himself who on Sunday announced news of his operation to the world during his weekly Sunday prayers, telling the crowd in St Peter's Square that doctors had found a nodule on his lung. (BBC)