What Is Radiotherapy?

Radiotherapy or radiation therapy is a type of cancer treatment that uses a high dose or intensity of radiation to stop the growth and multiplication of cancer cells or kill them. It uses high-energy particles, x-rays, gamma rays, and proton or electron beam therapy to destroy cancer cells.

Types of Cancers Treated With Radiotherapy

Radiotherapy can be local or systemic, depending on how the radiation is administered.

The aim of radiotherapy varies based on the characteristics of your cancer and your overall health and fitness. It would usually be one or more of the following:

  • To reduce the size of the tumour (in early-stage cancers)
  • To cure the cancer
  • To prevent recurrence
  • To treat symptoms of advanced-stage cancers
  • To treat cancer that has returned


Who Is A Candidate For Radiotherapy?

Each type of radiotherapy is indicated for different cases of cancer. While external radiotherapy is used to treat a majority of cancers, brachytherapy is preferred for treating cancers of the head and neck region, breast, cervix, prostate and eye. Systemic radiation therapy with radioactive iodine (I-131) is used to treat thyroid cancer.

In some advanced prostate cancers or gastroenteropancreatic neuroendocrine tumours, targeted radionuclide therapy is used. 

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Radiotherapy Procedure

There are two primary types of radiotherapies- internal and external. The type of radiotherapy recommended for you by your doctor will depend upon factors, such as:

  • The type and stage of your cancer
  • The size of the tumour
  • Nature of spread 
  • Your overall health and fitness
  • Your age
  • History of other chronic medical conditions

External Radiotherapy

External radiotherapy uses a machine that aims high-energy radiation at your cancer cells to destroy them. The machine moves around you, emitting radiation to a specific part of your body, making this treatment a localised one. The Linear Accelerator or LINAC is the most commonly used machine for this radiotherapy.

External radiotherapy can be of various types, and the most suitable option is suggested for you based on the type of your cancer and its location in the body:

  • Conformal radiotherapy
  • Intensity Modulated Radiotherapy (IMRT)
  • Image-Guided Radiotherapy (IGRT)
  • Stereotactic Radiotherapy (SRT)
  • Proton beam therapy
  • Superficial Skin Radiotherapy 


Internal Radiotherapy

In internal radiotherapy, the radiation source (usually a solid or liquid) is placed inside your body. This treatment can be of two types, namely:

  • Radioisotope or radionuclide therapy: You will be given a radioactive liquid in a drink, capsule or injection form for this procedure. This liquid is attached to an isotope that guides it to the cancer cells. This is a type of systemic radiation therapy.


  • Brachytherapy: During this form of internal radiotherapy, a small radioactive material is put inside the body, as close to cancer as possible. This treatment is most commonly used for prostate, cervical and uterine cancers. The radioactive material covered by the implant is left in the body for a few minutes, days or permanently to kill the cancer cells. Like external radiotherapy, brachytherapy is a type of localised radiation treatment.

Benefits of Using Radiotherapy In Cancer Treatment

The main advantage of radiotherapy is that it may help to control the growth of the cancer.

Each treatment session will take about 30 minutes, or longer for SABR and usually it is completed as out patient.

Most patients are able to carry on with their daily life, such as going to work, if they feel up to it.

If there is presence of  advanced cancer, radiotherapy can help control symptoms and relieve pain.

Side Effects of Radiotherapy

Radiation therapy may cause short-term and long-term side effects, and your doctor will discuss the same with you before starting treatment. Common side effects like tiredness or fatigue will improve after a few weeks of treatment. 

Though radiotherapy treatment side effects will be limited to the area that is being treated, generalised side effects include:

  • Tiredness 
  • Weakness and fatigue
  • Sore skin that may become red, sensitive, dry and itchy
  • Hair loss in the treated area


Depending upon the area being treated, some long-term side effects of radiotherapy are:

  • Change in skin colour in and around the treatment area
  • Red spider-like marks on the skin due to broken blood vessels
  • Dry mouth
  • Reduced sex drive
  • Changes in bowel movements, loss of appetite
  • Inflammation of the bladder
  • Infertility issues
  • Breathing trouble


Sometimes, the physical side effects of radiotherapy can also weigh in on you emotionally. Discuss how you feel with your doctor, healthcare team, or a loved one. Throughout your radiation therapy, you must remain positive as it reflects in your physical health and well-being.

Undergoing radiotherapy for your cancer treatment can be challenging, but your healthcare team will help you through it– from emotional support to helping you manage the side effects. Feel free to discuss your concerns with them. If you are unsure about any part of your treatment, seek a second opinion from another doctor who specialises in cancer.




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If you need to speak to a specialist about undergoing a radiotherapy procedure for your cancer or seek a second opinion, reach out to us right away!

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