On May 18, 2025, it was announced that former President Joe Biden had been diagnosed with an aggressive form of prostate cancer. His diagnosis followed a medical examination due to worsening urinary symptoms and a prostate nodule (here are some other prostate cancer warning signs you shouldn’t ignore). The statement revealed that his cancer was “characterized by a Gleason score of 9 (Grade Group 5).” It was further noted that the cancer appears to be hormone-sensitive, which indicates that there are treatments available to manage it (via CNN).
Once news about Biden’s diagnosis emerged, many were eager to understand what these numbers mean for the former president’s prognosis, especially after President Donald Trump inaccurately claimed that Biden has “Stage 9” cancer (it’s actually Stage IV). NCPIC consulted Dr. Justin Houman, a board-certified, fellowship-trained urologist, to gain a clearer understanding of what these scores signify.
The first point Houman emphasized was the distinction between “stage” and “Gleason score.” “There is no such thing as ‘Stage 9’ cancer,” he clarified, explaining that Biden’s Gleason score of 9 pertains to a grading system used specifically in prostate cancer.
What the difference is between stage and Gleason score
“Staging tells us how far the cancer has spread,” said Houman, adding that a TNM (tumor, nodes, metastasis) system is used to stage cancer. This system examines the size and extent of the primary tumor within the prostate, whether it has spread to nearby lymph nodes, and whether it has spread to other organs. “Prostate cancer is commonly grouped into Stage I to Stage IV, with Stage IV being the most advanced,” he said. In Biden’s case, it has been reported that his cancer has metastasized to the bones, placing it in the category of Stage IV. (Learn more about the four stages of prostate cancer, and what happens at the end.)
“Gleason Score, on the other hand, tells us how aggressive the cancer looks under the microscope,” Houman said. This score starts at 6 and goes up to 10. Houman added that it’s actually the sum of two numbers, which is why the score doesn’t start at 1. “A Gleason 9 means the cancer is high-grade and aggressive, even if it hasn’t yet spread beyond the prostate,” he explained.
Why the stage and Gleason score are important to understand
Houman emphasized the importance of understanding both the stage and Gleason score, as the stage indicates the location of the cancer, while the Gleason score reveals its behavior. “So when we hear that someone has a Gleason 9, it means they have a highly aggressive form of prostate cancer, but not necessarily a widely spread (Stage IV) cancer,” he explained.
Houman further noted that treatment decisions depend on both of these factors. “A high-grade cancer caught early (Gleason 9, Stage II) might still be curable,” he said. “But a lower-grade cancer that has already spread widely (Gleason 6, Stage IV) could be much harder to treat.”
While Houman didn’t comment on Biden’s prognosis specifically, the Wall Street Journal reported that, although Stage IV prostate cancer isn’t curable, experts say the former president could “live for years.”
