Pope Leo Diagnosed With Lung Cancer: What You Need to Know

Pope Leo, the leader of the Roman Catholic Church, has been diagnosed with lung adenocarcinoma — the most common type of lung cancer. The 71-year-old was taken to Gemelli Hospital in Rome after doctors found a tumor during a routine health check. On Tuesday, surgeons removed the lower lobe of his right lung to treat the disease. Leo himself said the growth was "well-contained" and had been caught early.

Doctors say lung adenocarcinoma starts in glandular cells, which are cells that make substances like mucus. In the lungs, these cells line tiny air sacs that help us breathe. This type of cancer makes up about 40 percent of all lung cancer cases, according to the Lung Cancer Foundation of America. It is the most common kind of a larger group called non-small cell lung cancer, which accounts for about 80 to 85 percent of all lung cancers.

One important thing about adenocarcinoma is where it grows. It usually forms in the outer parts of the lungs, away from the center. It also tends to grow more slowly than other types of lung cancer, which gives doctors a better chance of finding it before it spreads to other parts of the body.

Smoking is the biggest risk factor for lung cancer overall. However, adenocarcinoma is also the most common type of lung cancer found in people who have never smoked. The pope is not known to have ever been a smoker, so doctors likely found the tumor through his regular medical checkups rather than because of obvious symptoms.

In its early stages, lung adenocarcinoma often causes no symptoms at all, which is why it can go unnoticed for a long time. As the cancer grows, a person might experience a lasting cough, shortness of breath, or wheezing. Other signs can include coughing up blood, pain in the chest, shoulder, or back, unexplained weight loss, and feeling very tired.

When the cancer is still inside the lung and has not spread, surgery gives patients the best chance of being cured. The operation Pope Leo had is called a lobectomy, which means removing an entire section, or lobe, of the lung. Doctors prefer this method when the tumor is in just one lobe because it gives the best chance of taking out all the cancer while keeping as much healthy lung as possible. Depending on the stage of the disease, other treatments like chemotherapy, radiation, or immunotherapy may also be used.

The Vatican has not yet shared details about what follow-up treatment Pope Leo may need. Officials also have not said how large the tumor was or whether it had spread to any lymph nodes, which are small glands that help the body fight illness. Without that information, it is hard for doctors to predict exactly how Leo will do. His doctors and supporters around the world are watching his recovery closely.

Survival rates for this type of cancer depend a lot on how far the disease has spread. According to the American Cancer Society, about 67 percent of people with non-small cell lung cancer that stays inside the lung are still alive five years later. That number drops to about 40 percent if the cancer reaches nearby tissues or lymph nodes, and to about 12 percent if it spreads to distant parts of the body. Doctors also note that newer treatments are helping more patients live longer than older statistics might suggest.