A great cheer went up from some 20,000 people in St. Peter’s Square at midday on Sunday, Oct. 18, when a smiling Pope Leo XIV appeared at the window of the papal study on the third floor of the Apostolic Palace. It was the first time he had spoken publicly since undergoing surgery at Rome’s Gemelli Hospital five days earlier.

Looking well and speaking in a strong voice that showed no sign of weakness from the Oct. 13 operation, which removed the lower lobe of his right lung, the 71-year-old, Chicago-born pope began with a brief reflection on the day’s Gospel reading (Mt 22:15-21), in which Jesus says, “Give therefore to the emperor the things that are the emperor’s, and to God the things that are God’s.”

After reciting the Angelus with the crowd, the Augustinian pope, who spent some 20 years as a missionary and bishop in Peru, noted that the church was celebrating the 100th World Mission Day. He prayed “that the church may always remain faithful to the mandate of the Risen Lord: ‘Go into all the world and proclaim the good news to the whole creation’” (Mk 16:15).

He then spoke briefly about his week in the hospital:

“I would like to thank all those who have prayed for me in recent days. I have truly sensed your support. Thank you!” he said. “I wish to express my particular gratitude to the doctors, nurses and all the staff of the Gemelli Hospital. This experience has made me feel particularly close to all those who are living with illness or infirmity.”

He concluded: “Now that I have overcome this delicate phase, as you know, I will gradually resume my activities, always with God’s help and your prayers. Thank you once again. Thank you all! Have a good Sunday!”

The roughly 10-minute appearance brought joy to the crowd. It contrasted sharply with his appearance at the window the previous Sunday, Oct. 11, when he stunned the world by announcing that he would be hospitalized for surgery.

Notably, the pope made no mention of his trip to South America, scheduled to begin in 19 days. Before entering the hospital, he had referred to his intention to travel, and on Saturday his surgeon said there were “no clinical reasons” the trip should not take place. His silence suggests that a final decision has not yet been made. Instead, in carefully measured remarks, he spoke of “gradually” resuming his activities, an indication that he still has some way to go before a full recovery.

In an interview with Vatican News released after the pope left the hospital on Saturday, Dr. Stefano Margaritora, the surgeon who operated on him, said the tumor had been found entirely by chance. 

“The discovery of the pope’s malignant lung tumor was entirely accidental, as unfortunately often happens,” he said. “During routine abdominal examinations, this small spot was found in the chest, at the base of the lung. This is fairly normal because, when radiological examinations of the abdomen are performed, the lower part of the lungs is usually visible, since the diaphragm is shaped somewhat like a parachute. However, if this small spot had been a little higher up, it certainly would not have been seen.”

He said the operation was successful and that the pope’s recovery was going very well. 

“The lung’s re-expansion after surgery is proceeding according to the usual timetable,” he said, and “his overall condition is good.” He added that “it takes a couple of weeks to make a truly complete physical recovery after this kind of operation” and that “since almost a week has already passed, I believe the pope could be fully recovered in another 10 days or so.”

Asked whether the pope could still travel to South America as planned, Nov. 6 to 17, Dr. Margaritora said: “As for a long trip involving air travel in about three weeks, I would say there are no clinical reasons why it should not take place.”

But other factors could still affect whether the trip goes ahead, and whether some events might be dropped from the published program, Vatican officials told America. That is particularly true in Peru, where the schedule includes visits to Cusco, at about 11,000 feet, and to Pucallpa, in the Amazon region.

The results of the histological examination are also still pending. They are expected in the coming days, and certainly within the week. Doctors are examining the tumor removed from the pope’s right lung, as well as the lymph nodes taken during surgery. The results will show whether the surgery removed the cancer completely or whether it has spread, and his doctors will use them to decide what follow-up treatment, if any, is needed.

Dr. Mario Nosotti, president of the Italian Oncological Medical Association, told the Italian daily La Repubblica on Sunday that after lung surgery, “it is recommended not to travel by air for one or two months.” He acknowledged that there are no specific studies on the question and no fixed rule. As a surgeon, he said, he tends to advise patients to wait two months, though other doctors allow air travel sooner. 

The final word, he said, rests with the pope’s own doctors, who know his situation well. Still, he cautioned that flying too soon after the operation “could be imprudent,” because a lobectomy is no simple procedure, even when recovery is rapid.

Leo now resumes his work at the Vatican, which said last week that he would hold no private or public audiences through Oct. 20. It is not yet clear whether that period will be extended to give him more time to recover.

Gerard O’Connell is America’s senior Vatican correspondent and author of The Election of Pope Francis: An Inside Story of the Conclave That Changed History. He has been covering the Vatican since 1985.