Pope Leo XIV is expected to remain hospitalized for around a week after he had part of his right lung removed in an operation on Tuesday. The Vatican said tests had confirmed a diagnosis of lung adenocarcinoma, the most common type of lung cancer worldwide.

The Pontiff’s first night in Rome’s Gemelli Hospital was “calm,” the Vatican shared in an update Wednesday morning, and doctors have since said that Leo’s tests show his “recovery is progressing normally.”He has undergone respiratory physiotherapy, has begun walking around his room, and has “resumed eating normally.”Leo will be observed while further tests are performed on his removed cancer tissue, as doctors determine what treatments might be needed next.

Leo, 71, had publicly addressed his health during Sunday prayers in St. Peter's Square at the Vatican, during which he said doctors had discovered a “localized nodule” in his lung that required surgery. He thanked everyone for their "spiritual closeness" and said he entrusted himself to their prayers.

Following the news of Leo’s diagnosis, people across the world have sent their well wishes. U.S. Secretary of State Marco Rubio, a Catholic, offered his prayers to the first American Pope. President Donald Trump, who has previously criticized Pope Leo, has yet to publicly comment. European Commission president Ursula von der Leyen wished Leo a “full and speedy recovery,” while Canadian Prime Minister Mark Carney described the Pope as “a source of hope and inspiration for billions around the world.”

As head of the Catholic Church, Leo leads an institution with an immense global following. Figures released in March by the Central Office of Church Statistics of the Secretariat of State show that the number of Catholics worldwide stood at just over 1.422 billion in 2024.

While Leo focuses on his recovery, all papal audiences have been canceled until Oct. 20. His time away from the Vatican has prompted questions about who, if anyone, oversees the church while a Pope is hospitalized.

Here’s what to know about the role of the Pope and how the Vatican will run in his absence. What is the role of the Pope?

The Pope is the Bishop of Rome and, under Catholic canon law, is described as “the head of the college of bishops, the Vicar of Christ, and the pastor of the universal church on earth,” granting him “supreme, full, immediate, and universal ordinary power in the church.”

Miles Pattenden, a historian of the Catholic Church at the University of Oxford, says the Pope is essentially “the man who makes executive decisions about how the church is to be run [from] the appointment of bishops, cardinals, the canonisation of saints, [to] anything else that involves the Pope's personal legislative or doctrinal authority.”Beyond his role within the church, the Pope is also a key international figure, frequently speaking out on high-profile topics such as artificial intelligence and immigration, and making apostolic journeys abroad.

In June, Leo made his first major European trip to Spain in honor of Pope Francis, who in the final years of his life had expressed a desire to visit the Canary Islands, a major arrival point for migrants crossing the Atlantic from West Africa into Europe. In September, Leo also embarked on a four-day visit to France.

The Pope is scheduled to take a 12-day trip to Latin America on Nov. 6, which is set to include a stop in Peru, where Leo holds citizenship. The trip is set to go ahead as planned. TIME has reached out to the Holy See press office for comment. What happens if a Pope becomes sick, incapacitated, or is hospitalized?

The Vatican has detailed laws and rituals to transfer papal power if a Pope dies or resigns. But none of them apply when he is sick or even unconscious.

Unlike other positions within the church, Catholic canon law does not provide a clear mechanism for transferring the Pope's authority if he becomes unable to carry out his responsibilities. Canon 335 declares that when the Holy See is “vacant or entirely impeded, nothing is to be altered in the governance of the universal church.”The papacy becomes vacant only if the Pontiff dies or resigns, with a resignation required to be “made freely and properly manifested.”

“There is no alternative rule. The Pope is in charge, and there's no mechanism to say the Pope can't be in charge. There's no rules on that,” says Pattenden. "When the Pope is incapacitated, that's a serious problem for the governance of the church.”In February 2013, Pope Benedict XVI, then 85, gathered the cardinals and announced his resignation as leader of the Catholic Church, citing his “advanced age.”He became the first Pontiff to step down voluntarily in nearly 600 years. Pope Francis confirmed in 2022 that he had prepared a resignation letter shortly after being elected Pontiff in 2013, "in case of impediment due to health reasons."

The letter, the contents of which are unknown, was not used, as Francis remained in office until his death aged 88 in April 2025. His final weeks included an extended stay in the hospital as he battled a number of health issues.

“The church doesn't have a process or a procedure like, for instance, the U.S. Constitution, there's no equivalent to the 25th Amendment, and there's no ‘Vice Pope’ like the Vice President,” Pattenden says, remarking on the lack of a deputy as something that can be perceived as a “weakness in the church's constitution.”As such, “anything that requires [the Pope’s] personal or doctrinal authority” during a hospital stay would have to wait until the Pope is able to address such matters.

Pope Leo, who is fully conscious and already walking around, remains contactable and will likely be able to liaise with church officials, should any pertinent issues arise during his hospital stay. On Wednesday, Cardinal Luis Antonio Tagle presided over a mass in place of Leo, and read out a homily prepared by the Pope.

Interestingly, other positions within the church have clearer arrangements in place for periods of incapacity.

For instance, canon law provides for circumstances in which a diocesan bishop becomes unable to govern his diocese, allowing its day-to-day administration to pass to an auxiliary bishop, vicar general, or another designated official. What does the Roman Curia do?

The Pope already delegates the day-to-day running of the Vatican and church to a group of officials who operate whether he is in the Apostolic Palace or not, and whether he is conscious.

The Roman Curia is the central administrative institution of the Holy See, supporting the Pope in governing the Catholic Church and carrying out its wider responsibilities.

“It has lots of departments, called dicasteries, which continue running according to their present structure and instructions,” says Pattenden. “For instance, there's a dicastery of education that is involved in the running of Catholic universities, setting up links for them, seminaries, and schools, and so on, and there are lots of officials with delegated authority.”

Among the most senior officials is the Vatican Secretary of State, Cardinal Pietro Parolin, whom Pattenden describes as “the second most important person in the Vatican.”Parolin addressed Leo's surgery early Tuesday, expressing concern, while praising Pope Leo’s calm manner.

Other senior church roles include the Dean of the College of Cardinals—a position recently assigned to Cardinal Tagle. The dean is known for playing a key role in papal transitions and is often considered a top contender himself.

The camerlengo of the Holy Roman Church , a role currently held by Cardinal Kevin Farrell, also takes on specific administrative responsibilities when the papacy becomes vacant following a Pope's death or resignation. The camerlengo helps oversee the Holy See's administration and finances during this period, but notably does not assume the Pope's authority or become an acting Pontiff during hospitalization. As for now, the Vatican has not indicated that Leo is in any way incapable of performing or delegating his duties.

“It's very clear that Pope Leo wants to be as transparent as possible,” says Pattenden, who notes that “being reminded of the Pope's mortality in this way will cause people to think about the kind of broader questions about what might happen to a Pope who's in ill health.”