Just over three weeks ago, the most significant visit of Pope Leo’s pontificate looked to be in doubt. The 71-year-old’s lung cancer surgery led some in the Vatican to believe his trip to Latin America would be postponed or its intense schedule adjusted.

But Leo XIV is forging ahead with a grueling 12-day visit, which includes Uruguay, Argentina, and an emotional “homecoming” to Peru, the country where he served as a missionary and bishop for around two decades.

He plans to cover a lot of ground – around 19,000 miles – while in Latin America. From November 6 to 17, the pope is scheduled to take 14 flights (including two in a helicopter), give 36 speeches and participate in around 50 events in what is one of the most intense papal trips of recent years.

He will also visit Cusco, Peru, which is more than 11,000 feet above sea-level and where there is 35% less oxygen per breath. During the whole trip, he’ll travel to 10 cities, preside at large open-air Masses and vigils and meet with political leaders.

The trip, especially Cusco’s altitude, has raised questions about his health and the precautions being taken while there. It has also shone a light on a region that has profoundly shaped him and set his path to the papacy.

The pontiff had surgery last month to remove a third of his right lung after a small growth was discovered during routine checks, which was later confirmed as cancer. His surgeon, Dr. Stefano Margaritora, said afterward that there were “no clinical reasons why this visit should not take place,” and doctors have said he does not need further treatment.

Vatican officials told reporters that Pope Leo will have a medical team available to him for the trip but stressed that no special measures are being taken. “We’re speaking of a 71-year-old person in good health,” the Vatican spokesman said ahead of the visit.

He explained the pope will travel with the “ordinary medical assistance,” including doctors, nurses and an ambulance, which usually travels with the pope’s convoy. But the spokesman said he wasn’t going into too much detail as the pope does not have a “permanent condition.”And if the Vatican medical team needs any help, one of the journalists traveling with the pope is also a doctor.

Montse Alvarado, the new head of Vatican Communications, told journalists on Tuesday that the pope’s “stamina is fantastic,” and that “he’ll have plenty of medical care on board should something happen.”

Dr. Matthew Triplette, a pulmonologist from the Fred Hutchinson Cancer Center in Seattle, told CNN the risk of a medical emergency during the trip is “low” but that this could include “either a collapsed lung or blood clots.”Triplette said the pope may be advised to “take low-dose blood thinners or use exercises or compression devices” to lower the possibility of blood clots in his legs when flying, which could cause major issues if they spread to the lungs. He added that the pope may feel more fatigue with exertion, particularly because there is less oxygen available at altitude. In the aftermath of his surgery, many speculated that the trip would be canceled.

“I must confess that, until just a few days ago, I was among the few who had serious doubts about whether this trip could even take place,” Guzmán Carriquiry, a Uruguayan former Vatican official who worked on Latin American issues for nearly 50 years in the church’s central administration, told reporters on Tuesday. But he also pointed out that the pope’s health team gave him the green light.

“This suggests that his doctors believe the pope possesses a robust physical constitution; it also serves as a testament to the pope’s ardent desire and determination to go out and meet our people,” he said. But Carriquiry noted that he would have removed Cusco from the agenda if he had organized the trip.

While Leo XIV is known for his gentle, low-key style, he is determined. Answering a question from CNN, Alvarado said the pope “personally confirmed this trip with no changes,” and that he was looking forward to returning to Latin America.

The continent, and Peru in particular, is close to his heart, and Alvarado said the pope would speak off the cuff frequently in Spanish, a language he is fluent in.

“He’s going on this trip very simply because he wants to go,” is how Archbishop Paul Gallagher, the Vatican foreign minister, put it at an event in Rome at the end of last month.

The Peruvian part of the trip will be emotional, as Leo arrives there “as an adopted brother, adopted by the Peruvian people,” said Carriquiry.

The pope, who remains a Peruvian citizen, had three stints in Peru, having first arrived there in his 30s.

He also served as Bishop of Chiclayo in the northwest part of the country from 2015 to 2023. The pope will return to Chiclayo during the trip and is expected to receive a rapturous welcome.

Leo is remembered fondly in the city, where he was considered a hands-on bishop who was known to travel across his diocese on horseback. “The pope spent many years living amongst the simple, poor and devout people of rural Latin America in northern Peru, as a missionary and a pastor,” Carriquiry, who is the former secretary of the Pontifical Commission for Latin America, said.

Leo is expected to draw huge crowds when he’s there, with estimates of around 1.2 million people expected to attend his final Mass of the trip at Las Palmas Airbase in Lima.

He is also expected to draw huge crowds in Argentina, where more than a million people are expected to attend his Mass in Buenos Aires.

The late Pope Francis, the first Argentine pontiff, never made a visit to his home country, so Leo’s visit is one that is generating intense interest.

Francis never gave a clear reason as to why he didn’t visit Argentina.

Carriquiry, a close friend of the late pope, said it “remains an enigma.”Leo XIV’s visit will underline his plans to continue the reforms of his predecessor, but with his own distinctive style. The pope’s visit comes at a time when Argentine President Javier Milei’s “chainsaw” austerity measures have led to welfare spending cuts.

Milei has also equated state-led social justice programs with communism. Pope Leo, in contrast, has made the church’s social teaching and concern for the marginalized a central concern of his papacy.

His itinerary includes a visit to a federal prison in Buenos Aires and a stop at a care center for people with intellectual and physical disabilities in Claypole which has been affected by the Milei cuts. Both Milei and Peru’s President Keiko Fujimori are notable figures in Latin America’s right-wing surge.

They also enjoy support from the Trump administration, which Leo has publicly disagreed with — particularly on migration issues. Leo XIV would not have been elected pope had he not been sent to Peru as a young Augustinian missionary.

His time in Latin America put him on a path to be spotted by Pope Francis.

It was Francis who appointed the then-Rev. Robert Prevost as bishop in Chiclayo before later bringing him to Rome and naming him a cardinal.

All of this set him up as a candidate in the 2025 conclave. While Leo is the first pope from the United States and grew up in Chicago, his experience in Latin America has profoundly influenced his outlook.

In Peru, he served in the birthplace of liberation theology, a movement focused on social and political action to help the poor and oppressed. As a bishop, he was known for organizing practical assistance for those affected by floods or in need of medical equipment during the Covid-19 pandemic.

He served in a church in Peru which emphasized an inclusive model, giving greater roles to those not ordained as priests and bishops, including women.

Leo’s time in Peru also saw him exposed to the fallout of the clerical abuse crisis, including a major scandal involving a powerful Catholic group. The Vatican says the pope will have two meetings with abuse survivors during his trip, one in Argentina and another in Peru.

South America remains the continent with the largest Catholic population, although recent years has seen a decline in numbers, and the rise of evangelical churches. In Uruguay, the pope will be in the continent’s most secularized country.

Whatever the health challenges, Pope Leo is determined to carry out the most important foreign mission of his pontificate so far: a return to the country that adopted him, and to the region that helped shape the man who would become pope.