Pope Leo XIV has been diagnosed with lung cancer but had successful surgery to remove a lower lobe of his right lung, the Vatican has said in a medical bulletin.

The 71-year-old underwent the 90-minute surgery on Tuesday at Rome's Gemelli Hospital and was subsequently diagnosed with lung adenocarcinoma.

"After the operation, the Pope awoke normally and returned after a brief period of observation to his room on the 10th floor," the Vatican said in a statement.

It comes after the lump was detected during what the Vatican has described as "routine checks".

Earlier, large crowds gathered outside the hospital to greet the Pope, with some waiting for several hours.

They cheered greetings and well wishes as he passed, while he waved and smiled back through the lowered back window of his car.

He was then met by staff on the hospital steps. "I'm sorry," one of them commiserated, to which the Pope gave a smile and a shrug. "We're here for you," he was assured.

It was Leo XIV himself who on Sunday announced news of his operation to the world, speaking from the balcony in St Peter's Square after delivering the traditional Angelus blessing.

He said the nodule, or growth, on his lung was "contained" and had been found "at a very early stage", but that doctors had advised him to have it removed.

Gemelli's thoracic surgery team operated on the Pope, whose schedule has already been cleared until 20 October to give him time to recover.

Nodules are quite common and not necessarily cancerous. But doctors say when a lump is removed it will usually be tested to check for any sign of the disease.

The Vatican has stressed that the pontiff, who is generally thought to be fit, had no symptoms of infection or illness.