Nuclear medicine uses small amounts of radioactive substances to detect or treat disease. At Seattle Cancer Care Alliance (SCCA), our nuclear medicine specialists are part of nearly every patient’s care. They do imaging scans and read them to diagnose, stage and monitor cancer. They also provide therapies to stop or reverse cancer growth.
Nuclear medicine imaging
Imaging methods like X-ray, ultrasound and computed tomography (CT) are good at showing structures inside your body. They tell us about the size, shape and position of things. This includes both normal structures, like bones and organs, and abnormal masses, like cancerous tumors.
Nuclear medicine scans do something else, too. Along with making pictures of the structures, these scans give your physicians details about your body’s function, or how it is working. They allow us to measure processes in and around your cells. The results tell us about the cells’ health.
Before a nuclear medicine scan, a small amount of a radioactive drug is put into your bloodstream. This is done by intravenous (IV) injection.
Radioactive drugs are drugs that are linked with radioactive elements (radionuclides). They are also called radiopharmaceuticals. When they are given in small amounts, such as for scans, they may also be called radiotracers.
The radioactive drug travels through your body and builds up in certain places. For example, it may build up in one organ or in cells that have points (receptors) on their surface where that drug can attach. Diseased cells take up the drug in a different way than healthy cells.
Given in such a small amount, the radioactive drug has no effect on your body. But the energy it gives off can be detected by a scanner. This lets your team see where the diseased cells are.
The scan is made by a machine with a special camera that detects radiation. Using data from the scanner, a computer makes a picture of the inside of your body showing where the radiation is. Then your nuclear medicine specialist reviews this picture.
It is common to call places with more radiation “hot spots” or to say they “light up” on the scan. Either hot spots or cold spots may be signs of cancer or other disease.
Your physicians use nuclear medicine scans to tell what is happening in your organs and tissues and how well they are working. The scans can tell your physicians things like:
- If cancer cells are present (even if the tumor is too small to show up on other types of imaging)
- Where tumors are and how large they are
- Where cancer cells have spread beyond the main site
- If the cancer will respond to certain medicines you have not had yet
- How well the cancer responded to treatments you already had
- If the cancer is shrinking or growing compared to earlier scans or if it has come back after it seemed to be gone
By telling us about what is happening in and around your cells, a nuclear medicine scan can give us important information. It can tell us about your health before there are structural changes that would show up on CT or magnetic resonance imaging (MRI).
SCCA physicians use nuclear medicine scans to check for cancer in many parts of the body, such as the bones, endocrine (hormone) system, liver, lungs, heart, brain and other organs.
The scan we use most often is a PET/CT (positron emission tomography/computed tomography) scan. In a PET/CT, both PET and CT scans are done. Then the two types of pictures are put together into a single set of images. This combines details about structure and function.
We also perform SPECT (single-photon emission computed tomography) scans. Usually, we do a CT scan at the same time (SPECT/CT). These scans are useful for seeing how well a tumor has taken up a radioactive drug so we know whether a patient should keep getting nuclear medicine therapy. Sometimes a SPECT/CT can tell us if tumors are responding during treatment.
Another scan we use is a planar imaging scan. A planar imaging scan is often done to:
- Detect cancer in the bones. This may be called a bone scan.
- Check that heart function is normal before starting treatment that might damage the heart. This is also called a multigated acquisition (MUGA) scan or radionuclide ventriculogram (RVG).
For some planar scans, we may add a SPECT/CT scan to help detect an abnormality.
Nuclear medicine therapies
Physicians are always working on better ways to stop cancer cells while doing the least harm to the body’s healthy cells. Nuclear medicine therapies are one of these ways. They deliver radiation directly to cancer cells using radioactive drugs.
This is an area of active research among scientists and physicians. Studies are happening right now, including at SCCA, to find new options for treating many types of cancer. SCCA is a leader in offering nuclear medicine therapies for neuroendocrine tumors (NETs), prostate cancer and other diseases.
A radiopharmaceutical is a drug linked with a radioactive element. It is put into your bloodstream by infusion (injection). The drug travels through your body and builds up in certain places. For example, it may build up in one organ or in cells that have points (receptors) where that drug can attach. Then the drug delivers the radiation into these cells.
The key is to use a drug that binds to your type of cancer cells. The drug acts as a delivery method, taking “packages” of radiation where they are needed to treat your disease.
The radiation given for treatment is stronger than the radiation for scans. Because the goal is to kill cancer cells, larger amounts are given to damage the cells the drug binds to. This can also damage a small number of nearby cells.
Nuclear medicine therapies are more targeted than conventional chemotherapy or radiation therapy. Ideally, they work better at the level of your tumor cells with fewer side effects and less damage to your healthy cells.
For this type of treatment to work, scientists first need to find targets on cancer cells. Then they need to find or develop drugs that will seek those targets. So far, radiopharmaceuticals are approved by the U.S. Food and Drug Administration to treat a few types of cancer. These include certain neuroendocrine tumors (such as neuroendocrine tumors from the gastrointestinal system, paragangliomas and pheochromocytomas), prostate cancer that has spread to the bones and non-Hodgkin lymphoma. We expect that new therapies will soon be approved for prostate cancer that target all tumor sites, not just the ones in bones.
At SCCA, we offer all approved nuclear medicine therapies. Currently, the main option is lutetium-177 dotatate (Lutathera). It is used for certain neuroendocrine tumors and certain types of prostate cancer with a neuroendocrine component.
We also offer radium-223 dichloride (Xofigo). This is given to patients with prostate cancer that has spread to their bones.
SCCA physicians lead and take part in studies testing new therapies or ways to make existing therapies better. This means SCCA patients may have the chance to try treatment options that are not offered at all treatment centers.
Lutetium-177 dotatate (Lutathera)
Lu-177 dotatate is a nuclear medicine therapy. It is a type of peptide receptor radionuclide therapy (PRRT) used mainly for neuroendocrine tumors (NETs).
PRRT combines a compound called a peptide with a radioactive element, called a radionuclide. The peptide finds and binds to cancer cells. It delivers the radionuclide. Then the radionuclide emits energy (radioactivity) that damages the cancer cells.
PRRT may help:
- Relieve cancer symptoms and improve the quality of life
- Stop or slow growth of tumors or shrink tumors
In Lu-177 dotatate, the dotatate is the peptide, or delivery system. Lu-177 is the radioactive element that can damage cancer cells.
After this combination is put into your bloodstream, it travels through your body. When it comes to cells with receptors for the hormone somatostatin, the dotatate binds there and goes into the cells. Then it releases the radiation.
Dotatate is good at binding to cells that have many tightly packed somatostatin receptors, avoiding other cells. When drugs are good at binding to certain cells, we say that they target or are “highly selective” for these cells.
This treatment is only for people whose cancer cells overexpress somatostatin receptors. In most cases, this means people with NETs that started in the stomach, intestine or pancreas. (These are called gastroenteropancreatic NETs, or GEP-NETs.) It can also include people with paragangliomas or pheochromocytomas (types of NETs), some lung carcinoids or prostate cancer.
Your SCCA team can check the level of somatostatin receptors on your cancer cells. We do this with a PET (positron-emission tomography) scan. For the scan, you get the radiotracer gallium-68 dotatate or copper-64 dotatate. If the scan shows that your tumors easily take up either radiotracer, this is a sign they have many somatostatin receptors. It means they will take up Lu-177 dotatate, too.
Usually, physicians use Lu-177 dotatate for patients who:
- Have advanced or worsening tumors
- Are not eligible for surgery
- Do not get enough relief for their symptoms using other methods
Patients get Lu-177 dotatate through an infusion (injection) at SCCA South Lake Union. The entire infusion process takes about five hours. The radioactive drug infusion lasts for about 35 minutes. Most people have one infusion every eight weeks for a total of four infusions. This is an outpatient treatment; patients go home later the same day.
Your care team will include a nuclear medicine specialist, a nuclear medicine technologist and nurses who help with your care and any side effects.
Before you begin treatment, your care team will talk with you in detail about topics such as:
- Your diagnosis and how Lu-177 dotatate may fit into your treatment plan.
- What to expect during and after treatment.
- How to prepare for your infusions, like if and when to stop taking other medicines.
- How to relieve any side effects you might have.
- How to reach us if you have questions or concerns after you leave the clinic.
- Ways to limit the risk of radiation to other people. (The risk is very low but important.)
During your infusions, you will get three medicines:
- A medicine to prevent nausea, a common side effect
- Amino acids, which help protect your kidneys from radiation
- Lu-177 dotatate
In the days and weeks after each treatment, you will have lab tests and imaging scans. Your nuclear medicine specialist uses these to see where the Lu-177 dotatate went in your body and how it is affecting you.
The U.S. Food and Drug Administration approved Lu-177 dotatate for GEP-NETs in 2018. Today, researchers at SCCA and elsewhere continue to study its effects. We want to learn more about the best ways to help people who have neuroendocrine tumors or other cancers that respond to this treatment. For example, researchers are checking whether NET patients who benefited from Lu-177 dotatate will benefit from getting it again later in life if their NETs worsen.
A team of nuclear medicine experts will plan and provide your care and support you throughout the process.