Pope Leo XIV on Sunday announced he would be operated on "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 expected recovery time would be about one week.
Chicago-born Leo became the first US pope last year, after his Argentine predecessor, Francis, died on April 21, 2025, at age 88.
Francis spent weeks at Rome's Gemelli Hospital, where popes traditionally go for medical treatment.
Leo was elected leader of the world's 1.4 billion Catholics on 8 May 2025.
The former Robert Francis Prevost, less ebullient than his predecessor, has gradually imprinted his style on the Catholic Church's leadership, 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 war.
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".