FILE PHOTO: Sen. John McCain (R-AZ) speaks at a press conference about the National Defense Authorization Act in Washington, U.S., October 25, 2017. REUTERS/Aaron P. Bernstein/File Photo

WASHINGTON (Reuters) - Republican U.S. Senator John McCain is expected to miss an upcoming vote on a tax code overhaul, after his office said he had returned to his home in Arizona following medical treatment.

The Senate is expected to vote as early as Tuesday on tax legislation. But McCain, undergoing treatment for brain cancer, will be out of Washington until January, his office said on Sunday. Top U.S. Republicans said on Sunday they expected Congress to pass the tax bill.