Leo, the first pope born in the United States, marked a break from his predecessor, Francis, who started his papacy at age 76 but had already had a lung condition at a young age. A year into his papacy, Francis told reporters that he thought he would serve as pope for only two or three years before going “off to the house of the Father.” Francis lasted a dozen years, but toward the end of his papacy had a bad knee, intestinal problems and finally, pneumonia in both lungs.

Now, Leo, who was diagnosed with lung cancer on Tuesday, suddenly faces the same sense of urgency and questions of longevity that had hung over Francis.

The diagnosis poses a lurching shift in the outlook for a pope whose relative youth and health indicated he had decades to reign. It casts uncertainty over his travel schedule, his agenda and his efforts to unite the Church. And in the worst-case scenario, it raises questions about succession that most thought would not have to be addressed for years to come.

“The common consensus was he’s young, we’re in for a long papacy,” said Christopher White, a senior fellow at the Initiative on Catholic Social Thought and Public Life at Georgetown University and the author of “Pope Leo XIV: Inside the Conclave and the Dawn of a New Papacy.”

While Leo was not as young as Pope John Paul II, who was just 58 when he was elected in 1978, Leo’s apparent healthy lifestyle added to an impression of his vitality. “Leo has the profile of someone who takes care of himself,” Mr. White said. “So that has added to the shock.”

At his weekly general audiences in St. Peter’s Square or on international journeys, he showed no signs of impaired health and kept a hectic schedule. In Rome, his agenda was packed with meetings and over the summer he released a major document on artificial intelligence.

From the beginning of his papacy Leo, born Robert Francis Prevost in Chicago, behaved like someone who believed he could take his time. In the early months, he was considered slow to act. He made few personnel changes and did not immediately grab headlines with dramatic pronouncements or policy moves. He seemed more interested in soothing tensions and listening.

And even when Leo became more strident, as when he criticized the Trump administration’s war in Iran, he responded only when the president specifically attacked him, and then retreated, saying he did not want a fight. With his quiet, steady demeanor, he gave the sense that he was in no rush.

After Francis’s tumultuous papacy, during which conservative Christians balked at the progressive Catholicism he elevated, Leo was seen as a leader who could calm the Church. Leo has been popular not only with both progressive and conservative Catholics, but with people outside the faith who see him as a moral leader in troubled times.

His illness will inevitably unsettle the Church, particularly depending on how transparent the Vatican continues to be about the pope’s progress through treatment. “This kind of thing just creates disquiet,” said David Gibson, director of the Center on Religion and Culture at Fordham University.

For now, the pope, who recently traveled to Spain and France, has said he will keep to his plan to travel to Latin America in November. Inevitably, any changes to his schedule will be scrutinized closely.

The pope’s doctors announced that the surgery to remove a lower lobe of his right lung was successful and had no complications. Information released by the Vatican suggested the cancer was caught at an early stage.

If Leo makes a strong recovery, Mr. Gibson said, the cancer could become part of a heroic narrative that buoys Leo’s reputation. Pope John Paul II, who started out in excellent health, was seriously wounded by an assassination attempt in 1981 and spent three months in the hospital. His recovery became part of “the mythology that grew up around him,” said Mr. Gibson.

And while few people survive assassination attempts, many people live with cancer. Pope Leo’s illness and how he behaves during treatment could serve as an inspiration to others suffering from disease.

“There’s also an opportunity for him in this vulnerability to be as great a comfort to many people as he was in the first year and a half of his papacy,” Mr. Gibson said.

(http://www.autoadmit.com/thread.php?thread_id=5912688&forum_id=2#50189136)