Midway through his four-year term, Santos surprised the Andean nation on Monday by announcing that doctors had discovered a cancerous growth. He said the disease had been caught in time and there was minimal risk.

"The surgery took place without problems whatsoever ... recovery is taking place now," Santos' urologist Felipe Gomez told reporters outside the Fundacion Santa Fe hospital in northern Bogota where the operation took place.

Gomez made the comments roughly five hours after Santos checked into the hospital.

"The time has come. Here I am going in. I'm optimistic. God willing, everything will be fine," Santos told reporters before the surgery.

Doctors said the tumor was extracted under local anesthesia and that it had not spread. They are expected to give another update on Santos' recovery later on Wednesday.

"What we saw during the procedure is in line with the studies that were carried out before the surgery. The president is now in his room in full possession of his faculties," said Adolfo Llinas, the hospital's medical director.

Santos' treatment will not require chemotherapy, Gomez has said, and the president will likely spend two to three days in the hospital, while a complete recovery will likely take up to three weeks.

He is not allowed to travel during his recovery, but will be able to carry out his official duties.

GOOD PROGNOSIS

The Harvard-educated economist, who took office two years ago, said earlier this week that he had a 97-percent chance of beating the disease.

Santos, a conservative whose policies have fueled economic growth in the country, is about to start peace talks with the Revolutionary Armed Forces of Colombia (FARC), whose Marxist-inspired insurgency killed tens of thousands in half a century.

A peace deal would help secure Santos a place in history and allow him to build on the economic and security advances that began under former President Alvaro Uribe a decade ago.

Colombia, a nation of about 46 million, has attracted record foreign direct investment over the last few years as a U.S.-backed military offensive against drug traffickers and FARC rebels improved business confidence.

"Thanks to the (Patron Saint) of Miracles for the operation's result. Today more than ever we need the President," Vice President Angelino Garzon, who battled his own illness earlier this year, said via Twitter.

Santos joined several other Latin American leaders who have battled cancer in recent years.

Venezuela's Hugo Chavez, who seeks re-election on Sunday, has undergone three operations for tumors since mid-2011.

Former Brazilian President Luiz Inacio Lula da Silva was successfully treated for a throat tumor earlier this year and his successor, President Vilma Rousseff, was treated for lymphoma cancer in 2009.