Biden’s prostate cancer is ‘hormone-resistant’ — doctors break down what that means

Joe Biden’s recent diagnosis of “aggressive” prostate cancer has sparked concerns about how far the disease has advanced.

The former president’s prostate cancer has been characterized by a Gleason score of 9 (grade group 5) with “metastasis to the bone.”

The score of 9 indicates “high-grade” prostate cancer with very abnormal cells that are likely to grow quickly, experts say.

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

The fact that Biden’s cancer has been classified as “hormone-sensitive” means it could be more responsive to hormone therapies, and thus more treatable.

Hormone-sensitive prostate cancer needs androgens (male hormones) to grow, according to the National Cancer Institute. When those androgens are reduced or blocked, the cancer stops growing.

Dr. Marc Siegel, clinical professor of medicine at NYU Langone Health and Fox News senior medical analyst, said the hormone-sensitive designation doesn’t necessarily mean Biden has already been taking hormone therapies, which is unknown.

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“You can tell under a microscope if this is the type of cancer that could respond to hormone therapy, but no matter what it looks like, you don’t know until you try it,” he told Fox News Digital.

“And sometimes it looks like there will be an effect, but it ends up being resistant to therapy.”

Prostate cancer has long been known to feed on the male hormone testosterone, according to Dr. Bilal Siddiqui, M.D., a medical oncologist and prostate cancer researcher at The University of Texas MD Anderson Cancer Center.

“The overwhelming majority of prostate cancers — 99% plus — are hormone-sensitive and dependent on testosterone in the beginning,” he told Fox News Digital.

“I would say it’s a very reasonable assumption [of hormone sensitivity], but we would know definitively once hormone therapy has started.”

The backbone of treatment for any metastatic prostate cancer is “androgen deprivation therapy,” which is geared toward decreasing the body’s level of testosterone.

“Typically, when you start the androgen deprivation therapy, testosterone levels will decrease and the PSA levels will decrease along with it, and that’s your definitive proof that the cancer is hormone-sensitive,” Siddiqui said.

Historically, androgen (hormone) deprivation therapy was done surgically through removal of the testes — but today’s typical methods include pills or injections, according to the oncologist.

“That eliminates about 80 to 85% of the testosterone that’s produced in the body,” he said.

In many cases, doctors may add other drugs to block testosterone from secondary sources in the body, such as the adrenal glands that sit above the kidneys.

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North Carolina family physician Dr. Alexa Mieses Malchuk reiterated that prostate cancer that shrinks or slows in progression after blocking testosterone qualifies as hormone-sensitive. 

“This means that it grows or shrinks in relation to how much androgen or testosterone is circulating in the body,” she told Fox News Digital. 

“If you suppress testosterone and the cancer does not shrink and continues to grow or spread, then the cancer is independent of the amount of hormone circulating in the body.”

There are a number of different ways to monitor disease progression, but it’s most commonly done by a combination of PSA blood tests and imaging studies, the doctor noted.

Eventually, metastatic prostate cancer will progress to become hormone-resistant, which means it no longer responds to hormone therapy, according to Siddiqui.

“It can vary in how long it takes to get to that point,” the oncologist said. “It’s usually a couple of years before it evolves from hormone-sensitive to hormone-resistant.”

The “ultimate test” of whether cancer has become hormone-resistant is to lower testosterone levels and observe where the cancer goes, he noted.

There may also signs of the disease getting worse.

“That might mean a rising PSA (prostate-specific antigen) test, new pain or symptoms, or new tumors that show up on the scan,” Siddiqui told Fox News Digital.

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The U.S. Preventive Services Task Force states that men aged 55 to 69 years should have the option to undergo periodic prostate-specific antigen (PSA)-based screening to monitor for prostate cancer. 

“Before deciding whether to be screened, men should have an opportunity to discuss the potential benefits and harms of screening with their clinician and to incorporate their values and preferences in the decision,” the USPSTF states. 

Siegel questioned this guidance to skip screening for older men.

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“I don’t agree with guidelines to not test over 70 years of age, especially with so many treatments to offer for prostate cancer,” he said.

In addition to hormone therapy, some men may be candidates for robotic prostate surgery, chemotherapy and radiation, Siegel added.