Joe Biden's Prostate Cancer Has a Gleason Score of 9, but What Does That Mean?

After several days of discussion around Joe Biden's age following a new book on the subject, the former president announced on May 18 that he had been diagnosed with an aggressive form of prostate cancer. The news of Biden's cancer diagnosis has garnered plenty of press coverage, but some are also wondering how severe the illness actually is.

Biden, who has insisted up until recently that if he had run for a second term he would have beaten Trump, is now faced with a health issue that looks quite serious. Here's what we know about his diagnosis, including what it means that he has a Gleason score of 9.

According to the Cleveland Clinic, Gleason scores are a grading scale for prostate cancer. Low-grade prostate cancer grows more slowly than high-grade and is also less likely to spread. A score is determined after doctors examine a tissue sample under a microscope.

Scores range all the way from 1-10, with 10 being the highest grade of cancer. A score of 9 means that your cancer cells do not look like regular cells, and are therefore more likely to grow and spread at a rapid rate.

Gleason scores are just one piece of information used to inform a patient's overall prognosis, but a Gleason score of 9 aligns broadly with the overall description of Biden's cancer as severe. It's somewhat surprising that Biden's doctors did not catch the cancer sooner, but cancer is hard to detect, even in politicians who have access to some of the best medical care in the world.

Biden's announcement of the diagnosis has only intensified conversations around his age.

“Last week, President Joe Biden was seen for a new finding of a prostate nodule after experiencing increasing urinary symptoms,” his personal office said in a statement. “On Friday he was diagnosed with prostate cancer, characterized by a Gleason score of 9 (Grade Group 5) with metastasis to the bone.”

“While this represents a more aggressive form of the disease, the cancer appears to be hormone-sensitive which allows for effective management,” the statement continued. “The President and his family are reviewing treatment options with his physicians.”

“Gleason 9 is, by definition, aggressive, but you don’t know how bad it is unless you know what the PET scan looks like,” Dr. Alan Tan, genitourinary section lead at Vanderbilt University Medical Center told CNBC.

Biden's team is signaling that his diagnosis might not be a death sentence, but the score doesn't tell us all that much in isolation.

“Cancer touches us all,” Biden wrote in a post to X. “Like so many of you, Jill and I have learned that we are strongest in the broken places. Thank you for lifting us up with love and support.”

We'll likely learn more about his prognosis as he continues to receive treatment.