By Jan WolfeAug 8 (Reuters) – Former U.S. President Joe Biden’s prostate cancer has spread beyond his bones and is very painful, his son, Hunter Biden, said in an interview with the BBC. • “The cancer has spread, metastasized into his bones and further,” Hunter Biden told BBC’s “Newsnight,” according to video posted online on Friday. • A spokesman for the 83-year-old Democrat declined on Saturday to comment on Hunter Biden’s interview. • A Biden spokesman said in October he was undergoing radiation treatment and hormone therapy. • Biden’s presidential memoir is scheduled for release on November 17.