By The Associated Press

Pope Leo XIV had the lower section of his right lung removed after doctors diagnosed him with the most common form of lung cancer. While lung cancer is a leading killer, survival rates can be high if it’s caught early, as the pope’s tumor appears to have been. Here are some things to know.

What is lung adenocarcinoma?

The Vatican announced the pope’s diagnosis as lung adenocarcinoma, which is one of many forms of lung cancer.

There are two main groups, small cell and non-small cell lung cancers. The non-small cell kind make up the vast majority of the world’s cases and adenocarcinoma is its most common subtype. Even it comes in varieties that can grow faster or slower.

“While it’s still very dangerous, it has slightly higher cure rates than other types of lung cancer,” said Dr. John Heymach of the MD Anderson Cancer Center in Houston.

Smoking is the leading cause of lung cancer. But as many as 1 in 5 lung cancers occur in people who have never smoked and it’s not clear why, maybe in some cases just random chance, Heymach said.

Other risks include exposure to radon gas, asbestos, radiation, secondhand smoke and air pollution, according to the American Cancer Society.

How is lung cancer detected?

Lung cancer symptoms don’t usually appear until the cancer is advanced, according to the cancer society. They can include a persistent cough, chest pain, a hoarse voice, shortness of breath, and recurrent pneumonia or bronchitis — symptoms important to get checked.

Sometimes, lung cancer can be found early when someone has an X-ray or other scan that shows a spot in a lung that needs further investigation. That’s called an incidental finding, leading doctors to investigate well before symptoms and possibly early enough that the cancer remains small and hasn’t spread. In the pope’s case, a nodule in his lung was spotted during another exam.

In the U.S., yearly screening with a low-dose CT scan, a type of X-ray, is recommended for certain people at high risk because of heavy smoking.

Pope Leo XIV arrives at the Agostino Gemelli Polyclinic in Rome, Tuesday, Oct. 13, 2026, where he’s expected to be operated to remove a lung nodule. (AP Photo/Alessandra Tarantino)How is it treated?

Surgery is a mainstay when lung cancer is detected early, and increasingly is used even in more advanced stages. The pope had the lower section, or lobe, of his right lung removed to try to ensure that all of the cancer was removed.

The right lung has three sections or lobes while the left has two. Each lobe has its own airway branch and dedicated blood vessels and when one is removed, “the other lobes actually pick up some of the work,” said Dr. Ben Zhang, a thoracic surgeon at Allina Health in Minneapolis.

The lungs gradually compensate over several months until most people, especially those who already were physically active, notice little to no difference with exertion, he said.

The pope is known to engage in weekly tennis games and swimming.

In the U.S., the average hospital stay after lung cancer surgery is two nights, Zhang said. It depends in part on how quickly the patient can get up and walk around, as well as pain and how long a tube that can drain air and fluid from the chest is needed.

The pope was walking the next day, which Heymach called “typically a harbinger of a quicker recovery.”

Whether additional treatment is needed depends on the tumor’s stage, based on factors such as its size and whether it shows signs of spreading via the lymph nodes, and if markers on its cells suggest it may be aggressive. Additional treatment can be chemotherapy, used before surgery to shrink a tumor or afterward to attack any lingering cells. Other options include radiation, immunotherapy or what are called targeted drugs aimed at specific molecular drivers of a tumor.

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