Petraeus, 56, was diagnosed with early-stage prostate cancer, which was not publicly disclosed at the time because Petraeus and his family regarded his illness as "a personal matter" that "did not interfere with the performance of his duties," said his spokesman, Col. Erik Gunhus. President Barack Obama and top members of his administration were informed, he said.
As commander of a region running through the Middle East and across Central Asia, Petraeus did make at least one overseas trip during his treatment.
The Pentagon termed Petraeus' treatment "successful." He was treated at Walter Reed Army Medical Center.
In recent months, Petraeus has been noticeably on the sidelines of the public debate over how to salvage the war effort in Afghanistan.
Known mainly for the troop build up in Iraq that helped calm the war there, Petraeus once had great star power and used it publicly. He was a darling at Capitol Hill hearings and had former President George Bush's ear in regular video conferences to talk about military matters, a relationship that doesn't exist with the Obama White House.
As the head of the U.S. Central Command, he is still very much involved in the conversation about the two ongoing wars, debating the new Afghan strategy with the National Security Council and flying late last month to Germany for a meeting with the commander in Afghanistan.
But he has taken such a low profile publicly of late that some inside the Washington beltway speculated that he was contemplating a run for the presidency in 2012, something his adviser have denied.
The more prominent public face of the current war debate is Gen. Stanley McChrystal, sent in the summer as Obama's hand-picked commander of U.S. and NATO troops in Afghanistan. Petraeus has said that he supports McChrystal's assessment of the campaign and McChrystal's call for more troops, a position finding limited favor in the administration.