President Trump said Monday that he was surprised that Joseph R. Biden Jr.’s cancer diagnosis was not made public a “long time ago,” seeming to suggest without evidence that the former president’s cancer was not newly discovered and had been covered up.

Donald Trump reacted to the news of Joe Biden’s prostate cancer diagnosis by flexing his own clean bill of health Monday. The president also followed his son’s lead in casting doubt on how long his predecessor had known about his “Stage 9” cancer.