- The operation was to take place in the Gemelli hospital in Rome, which has frequently treated popes since John Paul II.
Pope Leo XIV announced on Sunday that he would have an operation "in the coming days" for a lump on his lung, saying it had been located "at a very early stage".
"During recent medical checks, a nodule on my lung was found. It has been detected at a very early stage and is very localised," the 71-year-old said in a weekly address in St Peter's Square.
"The doctors believe it would be right to intervene and so, following their advice, I have decided to have the operation to remove it. The operation is already planned in the coming days," he said.
Following the pope's statement during his Angelus prayers, the Vatican press office said the pontiff was expected to have surgery in the next few days, and the expected recovery time from the operation would be around one week.
The operation was to take place in the Gemelli hospital in Rome, which has frequently treated popes since John Paul II.
No information has been given as to whether the surgery and recovery would affect the pope's agenda for international trips. He is next due to go to Uruguay, Argentina and Peru between November 6 and 17.
- 'Calmness' -
In Chiclayo, a city in Peru that Leo is due to visit, members of the faithful expressed hope for his quick recovery.
"A lung nodule is no small matter. Let's hope God grants him the ability to travel by air and that he gets better soon," said Olga Pol, 62.
"The people of Peru are eagerly awaiting him," she added.
"I'm certain that all of Peru is praying for the pope and that he'll pull through," retired journalist Diana Celi said.
"God willing, we will have him here, because these preparations have been going on for several months -- not just on a practical level, but also on a spiritual one."
Italian Prime Minister Giorgia Meloni said in a statement that the "calmness with which he spoke during today's Angelus reassures us".
She expressed to the pope her "personal closeness, and that of the Italian government, as he confronts this ordeal of the coming days".
Ukrainian President Volodymyr Zelensky wished Leo a "successful surgery and a swift, full recovery" in a post on X.
"Our thoughts and prayers are with him, and we hope he will soon be back in good health and strength," he added.
Archbishop Daniel Sturla of Montevideo called on the faithful to pray for the pope's "speedy recovery" and to continue preparations for his upcoming visit to Uruguay "with even greater enthusiasm".
Argentina's bishops' conference also urged Catholics to join in a special prayer for Leo ahead of the surgery, asking that it "go well" with a "swift and full recovery".
Chicago-born Leo became the first US pope last year following the death of his Argentine predecessor Francis on April 21, 2025 at the age of 88.
Leo was elected leader of the world's 1.4 billion Catholics on May 8, 2025.
The former Robert Francis Prevost, while less ebullient than his predecessor, has gradually imprinted his style on the leadership of the Catholic Church, finding his voice as he takes on some of the world's most pressing issues, from bloody conflicts to artificial intelligence.
After the US and Israel launched a war against Iran in February, the pope became a high-profile critic of the conflict.
He condemned US President Donald Trump's threat to destroy Iran as "truly unacceptable" and urged Americans to demand that US lawmakers "work for peace".
Trump slammed the pontiff as "WEAK on Crime, and terrible for Foreign Policy" -- to which Leo replied that he had a "moral duty to speak out".