Systemic radiation therapy

See also

• List of medical treatments
• Healthcare
• Medicine
• Surgery
• Pharmacology

External links

• World Health Organization
• National Institutes of Health

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Systemic radiation therapy is a form of radiation therapy used in the treatment of certain types of cancer. Unlike external beam radiation therapy, which targets a specific area of the body, systemic radiation therapy involves administering radioactive substances that travel throughout the body to target and destroy cancer cells. This therapy is particularly useful for cancers that have spread to multiple areas or are not easily accessible by localized treatments.

Mechanism of Action

Systemic radiation therapy works by delivering radioactive isotopes that emit radiation capable of damaging the DNA of cancer cells. These isotopes are typically bound to molecules that target specific cancer cells, allowing for selective uptake by the tumor. Once inside the cancer cells, the radiation emitted by the isotopes causes DNA damage, leading to cell death.

Common Radioisotopes Used

Several radioisotopes are commonly used in systemic radiation therapy:

• Iodine-131 (I-131): Used primarily for treating thyroid cancer and hyperthyroidism. I-131 is taken up by thyroid cells, where it emits beta radiation to destroy cancerous tissue.
• Lutetium-177 (Lu-177): Used in the treatment of neuroendocrine tumors and prostate cancer. Lu-177 is often attached to molecules that specifically target tumor cells.
• Radium-223 (Ra-223): Used for treating metastatic castration-resistant prostate cancer with bone metastases. Ra-223 mimics calcium and is absorbed by bone tissue, where it emits alpha particles to kill cancer cells.

Indications

Systemic radiation therapy is indicated for:

• Thyroid cancer: Particularly effective for papillary thyroid carcinoma and follicular thyroid carcinoma.
• Neuroendocrine tumors: Often treated with peptide receptor radionuclide therapy (PRRT) using Lu-177.
• Prostate cancer: Especially in cases with bone metastases, treated with Ra-223.
• Non-Hodgkin lymphoma: Certain types can be treated with radioimmunotherapy.

Administration

The administration of systemic radiation therapy involves:

1. Patient Evaluation: Assessing the patient's overall health, cancer type, and extent of disease. 2. Radioisotope Selection: Choosing the appropriate radioisotope based on the cancer type and target. 3. Dosage Calculation: Determining the correct dose to maximize efficacy while minimizing side effects. 4. Injection or Oral Administration: Depending on the isotope, it may be given orally or via intravenous injection. 5. Monitoring: Patients are monitored for side effects and response to treatment.

Side Effects

Common side effects of systemic radiation therapy include:

• Nausea and Vomiting: Often managed with antiemetic medications.
• Fatigue: A common side effect of many cancer treatments.
• Bone Marrow Suppression: Can lead to decreased blood cell counts, increasing the risk of infection and bleeding.
• Specific Organ Toxicity: Depending on the radioisotope used, there may be specific organ-related side effects.

Advantages and Limitations

Advantages

• Targeted Therapy: Systemic radiation can target cancer cells throughout the body.
• Non-Invasive: Unlike surgery, it does not require physical removal of tissue.

Limitations

• Systemic Side Effects: Can affect healthy tissues, leading to side effects.
• Limited to Certain Cancers: Not all cancers are suitable for this type of therapy.

Also see

• Radiation therapy
• Thyroid cancer treatment
• Prostate cancer treatment
• Neuroendocrine tumor
• Radioisotope therapy