Radiation Therapy

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What is Radiation therapy?

Radiotherapy is the practice of treating cancer with radiation, most often x-rays. Radiotherapy from inside the body is called internal radiotherapy, and from outside the body is called external radiotherapy.

It is a long-lived therapy which has evolved through time and technology. Now the medical world cannot be separated from this modality as they exist like two peas in a pod.  

Radiotherapy can be used to cure cancer, reduce the chance of cancer recurrence or help relieve symptoms. It can be used alone or with other treatments, such as chemotherapy or surgery.  

More than 40 per cent of cancer patients are given irradiation at some point during their treatment.  

Photons and protons are used to treat deeper cancers. Electrons are used for superficial cancers.  

Mechanism of radiotherapy  

A radiotherapy is a form of ionising radiation (high energy) that damages the DNA of the cancer cells in the treated area in order to kill them. Radiation is toxic to normal cells. This is the main drawback of radiotherapy.  

The cells do recover over a period of time, and healing occurs through fibrosis.  

External radiotherapy  

The most used device is a linear accelerator (LINAC), which produces radiation beams using electricity.

Radiotherapy fractions  

The total radiation dose is typically broken up into several fractions or smaller doses. Healthy cells can regenerate as a result of treatments. These fractions are given over several weeks.  

Radiotherapy relieves cancer symptoms, such as pain, and is called palliative radiotherapy. Palliative radiotherapy has fewer side effects than radiotherapy compared to curative care.  

Internal radiotherapy  

Internal radiotherapy delivers radiation inside the body. Internal radiotherapy can be divided into two main categories.

  • Radioactive liquid treatment (radioisotope or radionuclide therapy) is used for thyroid cancers.  
  • Brachytherapy (radioactive implant treatment) is used for cervical cancers.  

Internal radiotherapy delivers radiation from inside the body, hence affecting fewer cells and being used for smaller cancers.  

Radiotherapy side effects  

Short-term side effects  

Malaise, tiredness, sore skin and fever.  

Long-term side effects  

  • Change in skin colour, telangiectasia.  
  • Bladder and bowel inflammation. Blockage of lymphatics.  
  • Breathing problems, dry mouth, Sterility and infertility.  

Role of adding chemotherapy with radiotherapy  

Both chemotherapy and radiotherapy are usually given at the same time.  

This will accentuate the effects of radiotherapy and thus help in better tumour control.  

Neoadjuvant Radiotherapy  

Radiotherapy is usually given prior to surgery when the tumour is significant, or there is a spread beyond the primary organ of involvement. This will help reduce the tumour size and make it operable. The side effect is that it can cause fibrosis and make surgery difficult.  

Adjuvant radiotherapy  

In this scenario, radiotherapy is given after the surgery. This is done to sterilise the tumour bed, get better local control, and prevent local recurrence.  


As mentioned before, radiotherapy has been used for more than a century to treat cancers. Though it has evolved with technology, new techniques, and procedures, it still stands as an upcoming field. Yet access to all radiation modalities is still in need of improvement globally, especially in low- and middle-income countries.  


How does radiation therapy work?

Radiotherapy is used in cancer treatment. By altering their DNA, cancer cells in the treated area of radiotherapy are destroyed.

What adverse effects might radiation therapy cause?

It ranges from tiredness and malaise to infertility and breathing difficulties.

How do you know if radiation therapy is working?

After completing a course/session of radiation therapy, the consulting doctor may request a PET-CT to know how well the treatment has worked in fighting cancer cells.

Why is radiation therapy used?  

To treat cancer, lessen the likelihood of recurrence, or simply help with symptom relief, radiotherapy may be employed.


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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