Former President Joe Biden is battling an “aggressive” form of prostate cancer, his office announced on Sunday, adding his condition is characterized by a “Gleason score of 9.” His office also said Biden’s diagnosis included metastasis to the bone. Biden’s cancer diagnosis comes after a small nodule was found in the former president’s prostate after “a routine physical exam” on Tuesday. The discovery of the nodule “necessitated further evaluation,” his spokesperson said at the time.

In February 2023 — while the now-82-year-old former president was serving in the White House — Biden had a lesion removed from his chest that was cancerous, according to the former White House physician. Additionally, before entering office, Biden had several non-melanoma skin cancers removed with Mohs surgery.

As the world reacts to Biden’s medical news, ABC News has broken down what his condition means and what possible treatments can be done.

What to know about prostate cancer

Prostate cancer is a type of cancer that forms in the tissues of the prostate, the small gland in men’s prostate that produces semen, according to the National Institutes of Health (NIH)

It is the most common cancer and the second leading cause of cancer death among men in the U.S., according to the federal health agency.

The NIH reports an estimated 313,780 new cases of prostate cancer will be diagnosed this year — representing over 15% of all new cancer cases.

An estimated 35,770 deaths from prostate cancer will occur this year — representing 5.8% of all cancer deaths, according to the agency.

Prostate cancer has a five-year relative survival rate, meaning the percentage of people alive five years after diagnosis, is roughly 98%.

Generally, prostate cancer usually grows very slowly and finding and treating it before symptoms occur may not improve men’s health or help them live longer.

However, it is generally a more treatable type of cancer, even when it has spread further.

Roughly 12.9% of men will be diagnosed with prostate cancer at some point in their lifetime, according to the NIH. In 2022, there were an estimated 3.5 million men living with prostate cancer in the United States.

The median age of prostate cancer diagnosis is 68 years old, according to the agency, while the median age of prostate cancer death is 79.

While the agency reports rates for new prostate cancer cases have been rising an average 1.8% each year over from 2013 to 2022, death rates have been falling on average 0.6% each year over between 2014 and 2023.

What is a Gleason score?

The Gleason grading system, or Gleason score, refers to how likely the cancer is to advance and spread, but does not predict the outcome.

It’s way of describing prostate cancer based on how abnormal the cancer cells in a biopsy sample look under a microscope and how quickly they are likely to grow and spread, according to the NIH.

The Gleason score is calculated by adding together the two grades of cancer cells that make up the largest areas of the biopsied tissue sample, the NIH says.

The grading system usually ranges from 6 to 10.

Biden’s diagnosis of a Gleason score of 9 indicates his cancer is aggressive.

A score of 9 indicates that the cancer cells look very different from normal prostate cells and are likely to grow and spread rapidly. This places the cancer in Grade Group 5, the highest risk category, associated with a greater likelihood of metastasis and a more challenging prognosis. Yet, despite the cancer’s apparent aggressiveness, its hormone-sensitive nature offers a viable treatment pathway.

Possible treatment options

While Biden’s official treatment plan remains to be announced, possible options for the former president include hormone therapy, or androgen deprivation therapy (ADT), which can reduce levels of male hormones that can fuel prostate cancer growth.

This approach can effectively slow disease progression and manage symptoms, even in advanced stages where the cancer has spread to the bones.

Regular monitoring of prostate-specific antigen (PSA) levels is crucial, as rising PSA levels can indicate cancer activity and help assess treatment effectiveness.

Surgery is typically not an option in cases like Biden’s, when the disease has spread to the bone and is not confined to the prostate.

Following the former president’s diagnosis, the American Cancer Society released a statement, saying, “This news is a reminder about the tragic impact of prostate cancer in the U.S.”

“Early detection is key, and we are concerned given the 5% year-over-year increase in diagnosis of men with more advanced disease. We can and must do more to prevent late-stage diagnosis and death from prostate cancer,” the ACS said.