Joe Biden's cancer has a Gleason score of 9. Here's what that means.

Former President Joe Biden was diagnosed with an "aggressive form" of prostate cancer that spread to the bone, a spokesperson said on Sunday, May 18. Biden was diagnosed on Friday, two days before the announcement was made.

His cancer has a Gleason score of 9, Grade Group 5, according to the spokesperson. But what exactly does that mean?

Here's what people should know about the score and what it means for the 82-year-old's health.

What is the Gleason score?

The Gleason score is a grading system for prostate cancer, according to the Cleveland Clinic. It usually ranges from a 6, which is low-grade cancer, to a 10, which is considered a high-grade cancer.

The lower on the scale the cancer is, the more likely it will grow slowly.

Scores are then slotted into grade groups ranging from Grade Group 1 to 5, according to the American Cancer Society. This is a newer way to grade a patient's prostate cancer.

Scores categorized as Grade Group 1 will be most likely to grow and spread slowly, while Grade Group 5 is most likely to grow and spread quickly.

Biden's cancer is characterized as having a Gleason score of 9, Grade Group 5, which would mean the cells look very different from healthy cells and are likely to grow and spread more quickly.

How is one's Gleason score is determined?

The Gleason score is determined through something similar to a point system.

It uses 5 different grades or patterns to determine "how much the cancer looks like normal prostate tissue," according to the American Cancer Society.

Cancer cells in the prostate that are assigned a grade of 1 look most like normal prostate tissue, but grade 5 cells look "very abnormal."

The grades of the two most common patterns of cancer cells are added together to determine the Gleason score.

"For example, if the pathologist gives the cancer cells in the most common pattern a grade of 3 and the cancer cells in the second most common pattern a grade of 4, the total Gleason score is 7," according to the Canadian Cancer Society. "This is often written on the pathology report as 3 + 4 = 7 out of 10."

People with scores of 6 or higher will then have their cancer categorized into the grade groups mentioned above.

How is the cancer scored?

The Gleason score of prostate cancer is based on the results of one's prostate biopsy or surgery, according to the American Cancer Society.

Is a high Gleason score bad?

A high Gleason score is neither good nor bad, according to the Cleveland Clinic.

The scoring system is mainly a method used by one's health care providers to determine how fast the prostate cancer might grow and are used to create a patient's treatment plan.

"Prostate cancer is usually found early, and it often grows slowly," stated the Mayo Clinic.

Most men diagnosed with prostate cancer will not die from it, according to the American Cancer Society.

How common is prostate cancer?

It is one of the most common types of cancer, according to the Mayo Clinic.

In 2025, the American Cancer Society estimates that there will be around 313,780 new cases of prostate cancer, and 35,770 deaths will occur due to the cancer.

Around 1 in 8 men will be diagnosed with the cancer, while 1 in 44 men will die from it.

How to get checked for prostate cancer

Early-stage prostate cancer does not usually cause people to show any abnormal symptoms, according to the Mayo Clinic.

However, early-stage systems can include:

• Blood in the urine (signs of this are where urine looks pink, red or like cola).
• Blood in the semen.
• Needing to urinate more often.
• Struggling to start urinating.
• Waking up at night more often to urinate.

Signs that one has prostate cancer that has spread and become more advanced include the following:

• Accidentally leaking urine.
• Back pain.
• Bone pain.
• Erectile dysfunction.
• Feeling very tired.
• Weight-loss without trying.
• Weakness in the arms or legs.

Anyone who is worried that they are showing concerning symptoms should visit a doctor or health care professional.

Contributing: Zac Anderson, Joey Garrison, James Powel, Thao Nguyen; USA TODAY

Julia is a trending reporter for USA TODAY. Connect with her on LinkedIn,X, Instagram and TikTok: @juliamariegz, or email her at jgomez@gannett.com