Millions of people around the world are praying for Pope Leo after he was diagnosed with lung cancer Tuesday following an operation to remove a suspicious growth. 

The first American pontiff is now recovering from the operation during which doctors removed the lower lobe of his right lung, which contained the growth that was less than three centimeters. A biopsy of the nodule confirmed a diagnosis of lung adenocarcinoma, the most common type of lung cancer.

The 71-year-old Pope Leo will spend the next week on the tenth floor of Rome's Gemelli hospital. The Vatican called the 90-minute operation "a complete success" with no complications. Earlier, the Pope arrived at the hospital's main entrance, smiling and greeting well-wishers. Days earlier, he announced doctors found the growth during a recent check-up.

Tuesday evening, the faithful gathered in the hospital's chapel to pray for Pope Leo and others. Rome's Cardinal Baldassare Reina prayed, "Let us join together in prayer, asking the Lord to sustain our Pope Leo and to comfort all those who are hospitalized here."

Outside New York City's Saint Patrick's Cathedral, Americans offered support.

"We're all supposed to pray for each other, and he does carry the cross, and we're all supposed to carry the cross for each other," said one supporter. "I think this is all within God's plan," said another.

There's no word yet on whether Pope Leo will require any additional treatment such as radiation or chemotherapy. Additional analysis will determine whether the cancer spread beyond the portions that were removed. Oncologists say the surgery might have been enough because the cancer was caught relatively early and the nodule, as well as a large portion of tissue surrounding the nodule, were removed.  

Pope Leo is reportedly a non-smoker, although it is unclear whether he was exposed to high amounts of second-hand smoke during his lifetime. An estimated 20 percent of lung cancer patients are reportedly non-smokers. 

There is a family history, though. The Pope's mother died of cancer, and his brother is currently hospitalized in Florida with the disease.

The Pope said earlier this week he still plans to fly to South America on November 6th unless doctors recommend otherwise.