Doctors say Cristina Fernandez’s cancer was detected before it spread, and she has a very good chance of a complete cure.

Dr. Pedro Saco is leading the operation at private hospital in the suburbs of Buenos Aires. He is a veteran Argentine oncologist who specializes in cancers of the head and neck.

Fernandez flew to the Hospital Austral by helicopter early Wednesday and went under anesthesia several hours later. Doctors say they’ll be able to report results by midday.

Supporters gathered outside the hospital waving signs backing Fernandez and her late husband Nestor Kirchner, who died of a heart attack in 2010.