Former President Joe Biden's office announced on Sunday that he was diagnosed with an "aggressive" form of prostate cancer. Biden's office also said the cancer had metastasized, spreading to his bones. Although some people were left wondering why the cancer was caught only after reaching a Gleason score of 9, oncology experts told ABC News that it's not uncommon for older prostate cancer patients to receive a diagnosis after the disease has advanced or spread. "Prostate cancer is something that we always hope screening will identify early, when the cancer is all still inside the prostate," Dr. Alicia Morgans, a...