Definition & Overview
Radiopharmaceutical therapy is a nuclear medicine procedure used to diagnose and treat a variety of medical conditions. It works by administering radioactive compounds to a patient. The patient is then monitored using different imaging scans.
Radiopharmaceuticals are drugs that are composed of a radioisotope bonded to an organic molecule. The molecule delivers the radioisotope material directly to specific organs, tissues, and cells being targeted by the treatment. Since the radioisotope can be chosen based on its properties, the treatment can be very effective and efficient.
Who Should Undergo and Expected Results
Radiopharmaceutical therapy is beneficial for patients suffering from a wide range of medical conditions, including:
- Cancer (primary and metastatic)
- Bone cancer
- Prostate cancer
- Thyroid cancer
- Cancer of the lymph nodes
- Brain tumour
- Ovarian cancer
- Parathyroid cancer
- Polycythemia vera (a blood disease)
- Non-Hodgkin lymphoma
It can also be used to diagnose various medical problems, such as:
- Abscess and infection
- Biliary tract blockage
- Diseases of the blood vessels
- Diseases of the bone marrow
- Colorectal disease
- Iron absorption disorders
- Heart diseases
- Intact heart muscle damage
- Kidney diseases
- Lung diseases
- Liver diseases
- Pernicious anemia
- Red blood cell diseases
- Spleen diseases
- Salivary gland diseases
- Stomach problems
- Blockage of the tear ducts
- Urinary bladder disorders
In summary, radiopharmaceutical drugs offer the following benefits:
- Diagnose an existing disease or medical problem
- Treat the disease or medical condition
- Relieve symptoms, such as pain
- Reduce the risk of cancer-related death by up to 30 percent
- Improve patients’ quality of life
- Help prevent the potential complications of disease
Radiopharmaceutical drugs, specifically radioactive iodine or radioiodine, are especially effective in treating thyroid cancers. This is because the thyroid absorbs almost all iodine content in the blood. Thus, the radioactive iodine can be used to target treatment directly to the cancerous cells in the thyroid gland. This way, unwanted effects on other parts of the body can be avoided or minimised.
Another type of radiopharmaceutical, Phosphorus 32 or P-32, is also highly effective in killing cystic brain tumours without harming the healthy parts of the brain.
For metastatic cancers, radiopharmaceutical therapy is deemed more effective than the conventional radiotherapy technique, which delivers radiation from the outside. However, this conventional method, which is called external beam radiation, can be used alongside radiopharmaceutical therapy especially for patients suffering from severe disease and painful cancers.
One specific type of drug, Radium 223, has been proven effective in shrinking metastatic bone tumours in late-stage cancer patients.
How is the Procedure Performed?
Radiopharmaceutical therapy is often used as an adjunct treatment after a patient undergoes surgery. For example, cancer patients first have to undergo surgery to get rid of the tumour. After this, radiopharmaceutical therapy may be performed to destroy the cancer cells that get left behind.
Radiopharmaceuticals can be administered in many ways, including:
- Interstitial radioactive colloid administration – This technique works by placing the radiopharmaceutical drug in a body cavity.
- Radiolabeled monoclonal antibody by intravenous infusion – This technique delivers radiolabeled monoclonal antibodies into the patient’s veins through an IV tube. Radiolabeled monoclonal antibodies are man-made versions of the proteins produced by the immune system. These proteins offer especially targeted treatment because they can attack only a specific type of molecular structure. Thus, they can target only the cancer cells in a specific, direct manner.
- Intra-articular administration – This technique administers the radiopharmaceutical drug through an artery.
Once the radiopharmaceutical drug is administered, it is designed to travel directly to the part of the body that is being treated. The drugs are designed to build up there. Once they reach the target area, they give off radiation. The radiation is powerful enough to destroy cancer cells. This then effectively treats the disease.
The drug can be administered several times over an extended period. The specific treatment plan appropriate for each patient is determined by the doctor depending on the patient’s condition.
Possible Risks and Complications
While offering a more advanced, targeted treatment for several diseases, radiopharmaceuticals do come with some risks.
For one, it is normal for patients to experience heightened symptoms during the first couple of days following radiopharmaceutical treatment. The symptoms, however, will begin to subside and go away after a few days.
Additionally, radiopharmaceutical therapy can increase a patient’s risk of infection. This is because the drugs tend to lower white blood cell counts in some patient.
Also, radiopharmaceutical therapy can lower platelet counts. This means that patients also face a heightened risk of bleeding and bruising.
Due to these risks and potential complications, radiopharmaceutical therapy is commonly used only for patients who do not respond to other treatments. It is also used as an adjunct treatment for those who are undergoing other treatment methods, such as surgery.
Some patients may also be concerned about the radiation exposure. However, radiopharmaceuticals only release only small and safe amounts of radiation. The amount of radiation is adjusted based on the severity of the disease. Smaller amounts are also used when the procedure is only performed for diagnostic purposes.
To keep risks and complications under control, all potential radiopharmaceutical agents undergo a strict evaluation and demonstration process. During this process, the radiopharmaceutical should be able to demonstrate its potential benefits and show that it is harmless to the patient receiving treatment. Each radiopharmaceutical drug may go through 5 to 8 years of evaluation and demonstration before it is approved for use.
Maffioli L, Florimonte L, Costa DC, Correia Castanheira J, Grana C, Luster M, Bodei L, Chinol M. “New radiopharmaceutical agents for the treatment of castration-resistant prostate cancer.” Q J Nucl Med Mol Imaging. 2015 Dec;59(4):420-38. https://www.ncbi.nlm.nih.gov/pubmed/26222274
Pandit-Taskar N, Batraki M, Divgi CR. “Radiopharmaceutical therapy for palliation of bone pain from osseous metastases.” J Nucl Med. 2004 Aug;45(8):1358-65. https://www.ncbi.nlm.nih.gov/pubmed/15299062