Tests confirm the cancer had not spread

Follow-up testing has resolved the question left open when Pope Leo left Rome's Gemelli Polyclinic on Saturday, four days after his lung surgery. His personal physician, Dr. Luigi Carbone, and his surgeon, Dr. Stefano Margaritora, said final post-operative tests on the removed tissue confirmed the diagnosis of adenocarcinoma - the most common form of lung cancer - and showed the disease had not spread.

In a joint statement, the doctors said: "A subsequent oncology assessment confirmed that no further treatment is necessary". Had testing found signs of spread, for example through the lymph nodes, or an unusually aggressive form of the disease, additional treatment would have been offered.

A nodule found by chance

The pope had the lower lobe of his right lung removed last week, in the first major health event of his 17-month pontificate. Margaritora told Vatican News that the nodule was found by chance during routine abdominal examinations and that the pope had not been experiencing any symptoms.

Working from the hospital

Leo has kept up his duties since the operation. While still hospitalised he took a call with Russian President Vladimir Putin, and he has appeared in public twice at the Vatican: the Sunday blessing and Wednesday's audience in St. Peter's Square.

During the audience, the pope thanked the crowds for their support, saying: "Thank you! Thank you for the support of your prayers".

South America trip stays on

The Vatican statement on the pope's lung cancer removes the uncertainty hanging over his schedule. His next major engagement is a Nov. 6-17 trip to Uruguay, Argentina and Peru, which includes a dozen flights, two helicopter rides and stops at high altitude.

Margaritora said there was "no clinical reason" to prevent the South America trip.