RADIATION TREATMENT

Radiopharmaceuticals

External beam radiation is not the only way to receive radiation therapy. Radiopharmaceuticals are medicines that contain a small amount of a radioactive substance and are used to diagnose or treat medical conditions such as prostate cancer.

What are radiopharmaceuticals made of?

A radiopharmaceutical has three parts: a radioactive element that gives off radiation, a targeting molecule designed to find a specific type of cell or tissue, and a linker that holds the two together. Once in your bloodstream, the targeting molecule works like a homing signal, carrying the medicine to the cells it was built to find.

Some radiopharmaceuticals give off gamma rays, which show up on scans and help doctors see where cancer is. Others release alpha or beta particles, which are used for treatment. Those particles damage the DNA of the cancer cell, and when that damage can’t be repaired, the cell dies. Cancer cells are especially sensitive to this kind of damage.

Interesting fact: this approach isn’t new—not at all. Radioactive iodine has treated some thyroid cancers since the 1940s.

How are radiopharmaceuticals used in cancer treatment?

Because they travel through the bloodstream, radiopharmaceuticals can reach small areas of cancer throughout the body, including spots too miniscule or scattered to treat with external beams. That’s why they’re most often used when cancer has spread (metastasized) and surgery or external beam radiation are no longer effective or practical on their own.

Types of radiopharmaceutical treatment

Pluvicto treatment

Pluvicto (lutetium Lu 177 vipivotide tetraxetan) treats adults with PSMA-positive prostate cancer that has spread. PSMA, or prostate-specific membrane antigen, is a protein found on the surface of many prostate cancer cells. Pluvicto seeks out PSMA, enters the cell, and delivers radiation that destroys it from within.

Pluvicto may be used:

• Together with hormone therapy when the cancer hasn’t been treated with certain hormone medicines yet, or still responds to them
• After hormone therapy has stopped working, either when chemotherapy can be delayed or after chemotherapy

Xofigo treatment

Xofigo (radium-223) treats prostate cancer that has spread to the bones. It can also help prevent the symptoms this type of prostate cancer causes. Radium-223 behaves much like calcium, so the body sends it to fast-growing areas of bone, including bone metastases. Its radiation is strong but travels only a very short distance, which limits damage to nearby healthy cells.

Your doctor may recommend Xofigo when:

• Cancer in your bones is causing symptoms such as bone pain
• The cancer hasn’t spread to other organs, such as the liver or lungs
• Treatments that lower testosterone are no longer working

What to expect during treatment

Before you start any type of treatment, your care team will review your medical history, blood work, and every medication you take. Let your doctor know if you have low blood counts, kidney problems, or any other cancer or cancer treatment. If your partner is pregnant or could become pregnant, use effective contraception during Pluvicto treatment and for 14 weeks after your last dose, since radiopharmaceuticals can harm fetuses.

Receiving Pluvicto

First, you’ll have a scan to confirm your tumors carry PSMA. Pluvicto is then given through an IV in your arm, which can take up to 30 minutes, once every six weeks for up to six doses. Drink plenty of water beforehand and urinate often in the first hours afterward. You’ll also continue hormone (GnRH) therapy unless you’ve had both testicles surgically removed.

Regular blood tests will check your blood counts and PSA level, which usually drops when Pluvicto is working. If side effects occur, your doctor may recommend skipping a dose or stopping treatment.

Receiving Xofigo

Xofigo is an IV injection that takes about one minute. You’ll receive six injections four weeks apart, so your last one comes about four and a half months after your first. You may need to pause other treatments, such as chemotherapy or external radiation, during this time.

Radiation safety after treatment

Your body will give off a small amount of radiation after treatment, and your care team will give you written instructions for safety protocols. For one week after each Xofigo injection:

• Sit down to use the toilet, then flush and wash your hands well
• Wash clothes or linens stained with blood, urine, or stool separately
• Wear medical gloves when cleaning up body fluids

It’s still safe to hug and spend time with loved ones, including children and pregnant people. Because some security scanners can detect very small amounts of radiation, you’ll get a card explaining your treatment to carry for up to a month.