What Patients Should Know About Radiation Treatment for Prostate Cancer

Radiopharmaceuticals, defined by the National Cancer Institute as drugs that contain radioactive substances, are at the forefront of treating patients with prostate cancer, as one radiation oncologist explained in an interview with CURE®.

“The newest addition to the arsenal of treatments that we can use is Pluvicto [(lutetium Lu 177 vipivotide tetraxetan, also known as 177Lu-PSMA-617],” said Dr. Malay S. Rao, a radiation oncologist with Cooperman Barnabas Medical Center in Livingston, New Jersey.

Pluvicto, a radioligand therapy, was approved by the Food and Drug Administration in 2022 to treat patients with PSMA-positive metastatic castration- resistant prostate cancer, including those previously treated with other therapies including androgen receptor pathway inhibitors and taxane-based chemotherapy.

Rao spoke with CURE® about how drugs such as Pluvicto work. He also discussed treatments via hypofractionated radiation therapy and what the most important factor is for newly diagnosed patients with prostate cancer to consider.

CURE®: How does a drug like Pluvicto work to treat prostate cancer?

Rao: Pluvicto is a medicine that is injected into your blood. Depending on the type of equipment [the treatment center] has, it can take anywhere from one minute up to 30 minutes to infuse the medicine. The way the medicine works is there are these cell surface receptors that we call PSMA, standing for prostate-specific membrane antigens, and Pluvicto latches on to those cell surfaces, which typically are found more so on prostate cancer cells than any other cells in your body.

So, we exploit that mechanism where we're trying to target the medicine to just seek out the prostate cancer cells — unlike chemotherapy, which really targets all rapidly dividing cells in your body [and] that could include your hair, the lining in your gut, the Pluvicto's specific for that membrane receptor. Once it latches, it gets internalized into the cell, once internalized, it releases a small radioactive molecule or atom, which then deposits the radioactive dose, thereby killing that cancer cell.

I would imagine that because of this highly targeted approach, the overall impact on a patient’s quality of life is very different than it would be from previous standards of care.

You're right, given that it has a very targeted mechanism. These types of medicines are a much newer category with a different mechanism of action than the conventional chemotherapy agents. And I think, increasingly, we probably will see more use of this technology in the future application as we come up with more products driven to target different cancers, not just prostate.

Another topic I'd like to discuss is a hypofractionated radiation therapy. What is that and how is that used to treat prostate cancer?

Hypofractionated radiation therapy, the term itself means doing less fractions, meaning the number of treatments. Conventionally speaking, for decades now we've been doing prostate external beam radiation, for anywhere from about an eight- to nine-week course; 44 to 45 treatments has been the standard. The newer approach has been looking to see if we can do the same regimen quicker, faster, with fewer visits, yet maintain safety and maintain the same level of cure rates.

And, multiple studies have been done in North America, Europe, and they've all come to the same conclusion that yes, we can do what we did over nine weeks and cut it down to something as short as five to six weeks, thereby reducing health care costs, improving patient convenience and yet maintaining safety and efficacy.

For newly diagnosed patients with prostate cancer, what should they know in general about the array of radiation treatments that are currently available to them?

For newly diagnosed prostate cancer, the most important thing to consider is, is your cancer low risk, intermediate risk or high risk? We start by putting your cancer into one of these buckets, because that really narrows down our treatment options. And unlike most other cancers, what's unique here is low-risk prostate cancer can be further subdivided into very low risk, also. And sometimes the intermediate cancers can be divided into favorable or unfavorable.

And that distinction is important because often for low-risk prostate cancers, and depending on your age, favorable-risk intermediate prostate cancers, can be followed with active surveillance, which typically involves checking your PSA [prostate-specific antigen, a protein associated with the presence of prostate cancer in the body] with a blood test twice a year, maybe repeating the biopsy and/or MRI at the one year anniversary from your previous biopsy date.

So there's a lot of vetting we do to make sure you meet these criteria for active surveillance. The advantage of active surveillance being that it avoids the treatment-related side effects. It helps you maintain your sex life or your intimacy, if that's still an important factor in your quality of life. And many times, depending on the person in front of you, maybe that's high priority and they're not willing to forego that as a treatment side effect that often comes whether surgery or radiation, [patients] can develop permanent erectile dysfunction. That's the first thing that needs to be looked at. There's often staging studies that also accompany this diagnosis.

And last but not least, there's something called a genomic fingerprint of your cancer, which is really being utilized more and more frequently for prostate cancer. And it really analyzes the tissue specimen from your biopsy. And we send it to a lab, which then sequences your tumor's genomic sequencing, look for high-risk genes and then gives us the score, which we try to interpret as, "Is the fingerprint of your cancer low, indolent, slow growing, or do you harbor more aggressive genes that make your cancer aggressive?" So that's also another piece we've been incorporating into the decision making.

Transcript has been edited for clarity and conciseness.

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