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  • Anna Pham

The Application of Radiation Therapy

Updated: Aug 20, 2022

Edited by Sky Ye.



As society leans towards technology and advances, so does the understanding and development of medical treatments and interventions, a remarkable example of this being radiation therapy. Radiation therapy is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors. Radiation can also be used in small doses to conduct x-rays to view the body. Cancer continues to be a challenge in the 21st century but there are many treatments that stop the spread of cancer or shrink cancerous tumors like the application of radiation therapy.


Radiation therapy uses high-energy particles in processes such as x-rays, gamma rays, electron beams, or protons to destroy cancer cells. It works by damaging the genes of cancer cells which control how cells grow and divide. When radiation damages the genes of a cancer cell, it can no longer grow and divide. Not only does radiation therapy target cancer cells, but it can also potentially harm healthy cells nearby by disrupting its cell cycle. Although healthy cells can almost always recover post treatment, radiation therapy can cause major side effects such as hair loss, extreme fatigue, skin problems, and nausea.


There are two kinds of radiation therapy: external and internal beam/brachytherapy. An external beam, a local treatment, is a radiation therapy machine placed outside of the body that aims radiation at cancer cells targeting a specific part of the body. For example, if the cancer is located in the lungs, the radiation will be directed towards the chest. Internal/Brachytherapy (sometimes called liquid radiation), is placed inside the body, near the cancer cells. In this type of localized treatment, seeds, ribbons, or capsules that contain a radiation source are placed near the tumor, treating a specific part of the body.


 

External Beam Radiation Therapy



Fig 1. Shows how the linear accelerator directs high-energy beams at the areas affected by cancer


 

Internal/Brachytherapy



Fig 2. Shows an HDR (High Dose Rate) brachytherapy within the prostate


 

The type of radiation therapy used is dependant on the following factors:

  • Type of cancer

  • Size of cancer (the size of the tumor and the span of the impact on the body as a whole)

  • Location of tumor

  • General health and patient history

  • Tumor location in relation to non-cancerous tissue and its sensitivity to radiation

  • Other ongoing treatments

  • Age and medical conditions


While radiation therapy can treat just about every kind of cancer, it is used as a primary therapy treatment for malignant tumors. Malignant tumors contain cells that grow uncontrollably that can either spread locally or to other sites (cancerous). It can be used in combination with surgery, chemotherapy, and hormone therapy. However, there is a limit to the amount of radiation a specific part of the body can endure. The dosage will also depend on the type of cancer and other significant factors.


 

Systemic Radiation Therapy

In contrast to localized radiation treatments, systemic therapy targets the whole body rather than one specific area. Systemic radiation therapy uses radioactive drugs (radiopharmaceuticals/radionuclides) to treat certain types of cancer such as thyroid, bone, and prostate cancer. The liquid drugs are made up of a radioactive substance that can be swallowed or injected into a vein. These drugs travel throughout the body and collect in places where cancer cells are located. There are also radioactive drugs that can be used to help diagnose non-cancer related conditions.


 

Radioimmunotherapy

Radiation therapy can include combined therapies such as immunotherapy. Radioimmunotherapy (RIT) is a type of targeted radiation therapy that involves a small amount of radioactive material (radionuclide) combined with a molecule engineered in a laboratory (monoclonal antibody). The radioactive material acts as a tracer that can locate and attach to cancer cells and then deliver the monoclonal antibody directly to the cells. RIT may be used to treat some types of B-cell lymphomas, healthy B-cells changing into fast-growing cancer cells that don't die, and treat newly diagnosed patients. However, it is most commonly used when other treatments are no longer working.


Approximately 50% of all cancer patients will receive radiation therapy. Doctors use radiation therapy to treat just about any type of cancer. The goal is to get enough radiation into the body to kill the cancer cells while preventing damage to healthy tissue. This remarkable advancement has significantly impacted the field of medicine by proposing a method targeting cancer cells. When receiving radiation therapy, it’s best to know what to expect and how it works to be prepared for treatment.


 

References:

  1. Fact sheet: What is Radioimmunotherapy? SNMMI. (n.d.). Retrieved July 11, 2022, from https://www.snmmi.org/AboutSNMMI/Content.aspx?ItemNumber=29736

  2. Farelly, J., & McEntee, M. C. (n.d.). Principles and applications of radiation therapy. Clinical techniques in small animal practice. Retrieved July 11, 2022, from https://pubmed.ncbi.nlm.nih.gov/12831066/

  3. How radiation therapy is used to treat cancer. American Cancer Society. (n.d.). Retrieved July 11, 2022, from https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/radiation/basics.html

  4. Larson, S. M., Carrasquillo, J. A., Cheung, N.-K. V., & Press, O. W. (2015, June). Radioimmunotherapy of human tumours. Nature reviews. Cancer. Retrieved July 11, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4798425/

  5. MD Anderson Cancer Center. (n.d.). Radiation therapy. MD Anderson Cancer Center. Retrieved July 11, 2022, from https://www.mdanderson.org/treatment-options/radiation-therapy.html

  6. National Cancer Institute . (2019, January 8). Radiation therapy for cancer. National Cancer Institute. Retrieved July 11, 2022, from https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy

  7. University of Rochester Medical Center . (n.d.). Non-Hodgkin lymphoma: Radioimmunotherapy (RIT). Non-Hodgkin Lymphoma: Radioimmunotherapy (RIT) - Health Encyclopedia - University of Rochester Medical Center. Retrieved July 11, 2022, from https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=BLymT6


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