Signing off on the final routine medical examination of Joe Biden’s presidency, physician Kevin O’Connor declared the former US president to be a “healthy, active, robust 81-year-old male”.

But the diagnosis of an aggressive form of prostate cancer, said only to have been discovered last week, has raised questions over the transparency of White House physicians and their personal loyalty to the presidents they serve.

It is unclear whether the former president was screened for prostate cancer during his presidency and health bodies have warned that PSA testing is often unreliable.

As with all presidents, the responsibility of their medical care lies with the White House physician, who serves as the personal doctor to the leader of the free world.

They run a military-like operation providing round-the-clock medical care to the president, often accompanying them on Air Force One during domestic and international trips.