With Pope Leo XIV recovering in hospital on Thursday following his lung cancer operation, questions are swirling about how the illness could change his papacy, less than two years after his election.
The 71-year-old leader of the world's 1.4 billion Catholics had a part of his lung removed on Tuesday and is undergoing further tests to determine if he is cancer-free or needs further treatment.
In the meantime, the Chicago-born pontiff is expected to spend at least a few days recovering at the Gemelli Hospital in Rome.
In a note published by the Vatican, his doctors on Thursday said a chest X-ray "showed a good recovery of the operated lung".
"The post-operative course is progressing as expected," they said.
A Vatican source said the pope has not had any visitors aside from a few members of his entourage, and has been able to do some work in hospital.
But experts said the unexpected diagnosis will fundamentally change the papacy in some ways.
"Illness acts as a crossroads in a pontificate—it either accelerates its momentum or diminishes its power," Vatican watcher Giacomo Galeazzi wrote in La Stampa daily on Thursday.
Mikael Corre, Vatican correspondent for France's La Croix newspaper, told AFP the way Leo is perceived has shifted.
"No-one expected to be waiting for medical bulletins again so soon—certainly not with this particular pope, who was 69 at the time of the conclave" in which he was elected, he said.
When Leo's predecessor, Pope Francis, spent more than five weeks in hospital in early 2025, the Vatican began issuing regular medical bulletins detailing the pope's medical treatment and the critical episodes when his life was in danger.
In May 2025, tennis-mad Leo—a keen gym-goer— became the youngest man chosen to lead the Church since John Paul II almost 40 years earlier.
"He was the 'athletic pope' who also proved to be a great traveller," Corre said. "He may remain both but he will now also be a pope whose health is constantly scrutinised."
'Prudent'
Leo has cancelled all his audiences until 20 October and his near-term travel plans are uncertain, including a demanding scheduled trip to Uruguay, Argentina and Peru from 6 to 17 November.
He is expected initially to have a scaled-back schedule, with fewer public engagements.
"I think he is going to want to jump right back into things as much as he can. I think he'll push himself," said US Vatican expert Elise Ann Allen, who has written a biography of the pope.
"But he's also very prudent. Leo understands his limitations and he'll listen to them," she told AFP.
The world's first American pope has gradually imprinted his style on the Church leadership, speaking out on some of the world's most pressing issues, from conflicts to artificial intelligence.
He has also proved unafraid to criticise world leaders or defend himself against US President Donald Trump's attacks.
"We're not going to see him change his style," Allen said.
"Scares like this have a way of crystallising things for you, of what's important," she said. "He will be even more determined, I think."
'Shift priorities'
Some Vatican insiders think Leo's illness might "shift his priorities", meaning fewer trips and more appointments, Corre said.
Several appointments are expected soon, in any case.
Leo has yet to create any cardinals, the red-hatted Princes of the Church who will vote in the conclave to elect his successor.
Five heads of dicasteries—Vatican departments—have also reached retirement age but have yet to be replaced.
Leo inherited a divided Church, with liberal and conservative factions that bickered under his predecessor Francis.
While he has been tasked with overcoming such polarisation, there are those inside the Vatican who hope Leo's illness will spur him into replacing close allies of Francis in key dicasteries with more conservative figures, Corre said.
Others expect him to forge ahead instead with diplomatic efforts, which have already "brought great stability", Allen said.
"I think this health crisis has eased those frictions even further," she said.
"It's brought the Catholic Church together in support around Pope Leo in a very strong way," she said.