“The cancer has spread, metastasized into his bones and further," he said. "It’s very painful and it’s very debilitating in many respects.”

Biden, 83, was the oldest man to serve as U.S. president and his age was a source of concern for much of his four years in office. He and his White House advisers have faced intense criticism for allegedly concealing the extent of his problems, especially after he was forced to abandon his bid for re-election after a disastrous debate with his eventual successor, Donald Trump.