By Joshua McElwee
VATICAN CITY, Oct 18 (Reuters) - Pope Leo pledged on Sunday to slowly resume his usual activities as the leader of the world's 1.4 billion Catholics as he greeted crowds in St. Peter's Square during his first public event since undergoing surgery for lung cancer five days ago.
The 71-year-old pontiff had an operation on Tuesday to remove the lower lobe of his right lung, fuelling speculation about how his illness might change his 17-month papacy.
Smiling from a window of the Vatican's Apostolic Palace as he spoke to pilgrims below in a firm, clear voice on Sunday, the first US pope thanked people across the world for their prayers and said he would now begin to resume his normal schedule.
"Having overcome this delicate phase ... I will now gradually resume my activities, always with the help of God and your prayers," Leo said.
The pope, who was discharged from Rome's Gemelli hospital on Saturday, came to the window in the palace unaided and held his weekly midday appointment as usual.
He also urged pilgrims waiting below under cloudy skies to set aside any selfish ambitions and serve God "without compromise".
(Reporting by Joshua McElwee;Editing by Sara Rossi and Helen Popper)
