Radionuclide Therapy

What is radionuclide therapy?

The idea of radionuclide therapy is based on the discovery that tumor cells of certain cancers have tissue-specific markers on their surface, which serve as targets for radionuclides. Radionuclides are radioactive atoms that can accumulate with high precision in tumor cells and irradiate the cancer from inside.

Acting like a Trojan horse, the radioactive substance is taken up by the target cells. While it was developed for treating malignant diseases, it can also be used for the management of benign conditions.

The radiation range of these radioactive elements lies within the micrometer range, minimizing damage to the surrounding tissue.

How does radionuclide therapy work?

Radionuclides are atoms that have an unstable nucleus and therefore emit radioactive radiation. In modern medicine, radionuclides are used for both diagnostics and treatment. In diagnostics, radionuclides are primarily used as so-called tracers that accumulate in certain regions. Through the emission of radiation, these regions can be visualized. A well-known example of this principle is scintigraphy.

During therapeutic use of radionuclides, radioactive radiation is used to irradiate and weaken targeted tissues. In most cases, beta radiation is used, while on rare occasions alpha radiation can also be used. The radiation is strong enough to damage local cells and induce cell death. 

The radionuclides must be chosen carefully. While they are supposed to destroy the target cells effectively, they should not damage the surrounding healthy tissue. This is achieved by choosing a radionuclide with a limited range and precisely delivering it to the target site. The latter is realized through different mechanisms depending on the specific target.

In intracavitary radiotherapy, the radioactive substance is administered precisely into a pre-existing body cavity. A common example, where this approach is applied is brachytherapy for prostate cancer. The substances can alternatively be administered intravenously and are able to accumulate within the tumor through specific receptors or antibodies. Moreover, accumulation can also be achieved by using elements that are naturally metabolized. A common example of this principle is radioiodine therapy. 

Which diseases can be treated using radionuclide therapy?

For some cancers, characteristic surface markers have been identified, enabling the development of specific therapies. 

According to current scientific knowledge, prostate cancer, neuroendocrine tumors, bone metastases, thyroid cancer, non-Hodgkin lymphomas, and some benign thyroid disorders and inflammatory joint disorders can be treated using radionuclide therapy.

What forms of therapy exist?

The most commonly used forms of therapy are radioiodine therapy for thyroid disorders and radiosynoviorthesis for inflammatory joint disorders. Furthermore, relieving bone pain caused by metastases of breast or prostate cancer using radiopharmaceuticals has been established.

Radioiodine therapy

The radionuclide sodium iodide is administered intravenously during radioiodine therapy. As the thyroid metabolizes iodine, the administered substance is taken up by metabolically active cells. This therapy can be used to treat a wide range of thyroid conditions. These include hyperthyroidism, enlargement of the thyroid (goiter), and thyroid cancer.

Radiosynoviorthesis

In radiosynoviorthesis (RSO), the radioactive substance is injected directly into the affected joint space rather than administered systemically. The therapy aims to treat the inflamed synovial membrane to reduce pain. The procedure is most commonly used in rheumatic joint disorders, where the synovial membrane is pathological. As RSO is a minimally invasive procedure, it is an effective alternative to surgery and well-suited for elderly or high-risk patients. 

Treatment of pain caused by bone metastases

In general, every malignant cell has the potential to spread via the blood circulation or lymphatic system and to form secondary tumors in other tissues. Bone metastases most often occur in the spine and can cause severe pain. Cancers that commonly metastasize to the bones include breast, prostate, and lung cancer. In these cases, radioactive substances are administered intravenously. 

Course of radionuclide therapy

In most cases, the radioactive drug is administered intravenously on an outpatient basis, where it circulates through the bloodstream to the target cells. The irradiation happens from inside the cells, leading to their destruction. As a result, pain from metastases can be effectively relieved within a few days.

Usually, radionuclide therapy can be performed on an outpatient basis, and patients can leave the clinic after a short observation period. However, in some cases, a short hospital stay may be required. 

For example, patients undergoing radioiodine therapy typically stay at the hospital for three to seven days. In contrast, RSO is an outpatient procedure which can be performed in many nuclear medicine practices. Similarly, the treatment of bone metastases, hospitalization is not necessary.

What must be considered before treatment?

Certain examinations are required before the treatment can begin. These include, for example, PET/CT imaging for localizing the tumor or metastases. Bone scintigraphy is also often required.

In the case of radio iodine therapy for benign thyroid diseases, sufficient thyroid function must be confirmed beforehand. Moreover, high iodine exposure, for instance from certain contrast agents or medications, may interfere with the treatment.

In order to determine the required target dose, a radio iodine uptake test is performed with a weaker radionuclide. This test is usually performed during an outpatient visit approximately two weeks before the procedure. 

As radioactive substances are mainly eliminated by the kidneys, renal function tests are required. Depending on the patient’s general health and pre-existing conditions, additional testing may be necessary. These requirements are discussed in detail before the procedure. 

Risks and side effects

Due to the precise radiation of the target cells, serious side effects are rare. Similarly, because of the sparing of surrounding tissues, the risk of radiation-induced malignancy of nearby organs is reduced. 

Temporary gastrointestinal symptoms within the first few days after injection are possible but rare.

As the drug is eliminated through the kidneys, renal function must be checked prior to the treatment. In addition, adequate hydration after the procedure is recommended. 

The only serious side-effect that has been observed is suppression of the bone marrow, impairing blood cell functions such as coagulation and immune defense. However, the bone marrow cells usually recover. Nevertheless, a stable blood count is required to qualify for therapy.

Costs and insurance coverage

The costs of radionuclide therapy for bone pain caused by metastases using Xofigo are generally covered by both statutory and private health insurance. 

Other, new therapies may require an individual reimbursement request from the health insurance. In such cases, the treating physician has to justify the treatment decision to the insurer.

What physicians specialize in radionuclide therapy?

Handling radioactive substances requires specialized training for the medical personnel as well as specific technical facilities. Physicians with a specialization in nuclear medicine are certified for conducting radionuclide therapy. Depending on the medical indication for the treatment, they may work closely with specialists in other disciplines such as endocrinology or oncology.

To assist patients in finding a qualified physician for that specific condition, all listed physicians have been carefully reviewed and selected. They are all experts in nuclear medicine and specialize in performing radionuclide therapy. Benefit from the expertise and schedule your first consultation quickly and easily.