The goal of radiation therapy is to stop the spread of cancer by killing the cancer cells and shrinking the tumour

An abnormal growth of cells that gets out of control, leads to a cancer. More and more such abnormal cells stick together to form a mass of tissue that is called a tumour. Whether this tumour is fatal (malignant) or benign, is what a biopsy will confirm. In the case of malignant tumours, the oncologist will prescribe treatments in order to annihilate the cancerous cells or at least retard their growth and spread. Depending on the stage at which the cancer is and which part of the body is affected, the doctor charts out the next course of action. Radiation Therapy is one route to attack the cancerous cells.




Radiation Therapy also known as Radiotherapy, is a kind of cancer treatment that uses high energy beams (x-ray, photons) to destroy cancer cells and shrink tumours. High doses of radiation therapy attacks the very DNA of cancer cells. When the DNA is destroyed, the cells die – this means the cancer cell cannot multiply anymore. Dead cells are then eliminated by the body. As simple as it sounds, it’s not quite so.


Most often it takes several sessions of radiation before the treatment even starts impacting the cancer cells. It may take weeks of radiation to penetrate the cancer cells enough to damage its DNA. In some cases, Radiation may not even have an impact on the cancer cells, in which case alternate treatment will be prescribed by the doctor.


During radiation therapy, not just the cancer cells, but normal cells are also exposed to radiation. This means normal cells are also damaged during the course of the treatment. However, the damage is reversible. This is one reason sessions are scheduled keeping in mind the recovery of damaged normal cells.




Broadly speaking there are two types: External Beam Radiation Therapy and Internal Radiation Therapy.


External Beam Radiation Therapy is carried out via a machine that aims the high energy beams at a precise spot on the body. The machine does not come in contact with the patient but moves all around the patient in order to reach the spot from various angles.


In Internal Radiation Therapy, the source of radiation is put inside the body. When a liquid source is used it is called Brachytherapy. When a solid source is used it is called Systemic Therapy.


External Beam Radiation Therapy and Brachytherapy target a specific part of the body. However, in Systemic Therapy the source travels throughout the body through the blood seeking out and attacking cancer cells.




The goal of radiation therapy is to stop the spread of cancer by killing the cancer cells and shrinking the tumour. When radiation therapy will be prescribed to a patient depends on what the doctor wishes to achieve via the treatment. Radiation Therapy is used:


  • As the Primary Treatment for cancer
  • Along with other types of cancer treatments such as chemotherapy, surgery, hormone therapy, etc.
  • To reduce pain in advanced stages of cancer
  • To shrink tumours before surgery
  • During surgery to hit directly at the targeted spot, minimizing damage of normal cells.
  • To kill any remaining cancer cells post-surgery




Repeatedly exposing the body to radiation therapy can leave the individual fatigued. Nausea and vomiting are also common side-effects. Hair-loss in the targeted region can be expected too. In some cases this is permanent. Other side-effects depend on the part of the body receiving radiation therapy.


Radiation therapy to


  • The Brain can cause blurry vision and headache.
  • The Chest can cause shortness of breath, trouble swallowing and a cough
  • The Breast can cause swelling and tenderness
  • The Head and Neck can cause dry mouth, trouble swallowing and less active thyroid gland
  • The Pelvis can cause diarrhea, bladder irritation, frequent urination, sexual dysfunction and infertility
  • The Rectum can cause diarrhea, bladder irritation and frequent urination
  • The Stomach and Abdomen can cause diarrhea, skin changes and affect the urinary bladder


During the weeks of treatment the patient is closely monitored by the Radiation Therapy team. The patient will undergo several scans and tests for the doctor to keep track of the effectiveness of the treatment and to make changes if needed. Once the treatment is complete, following up with the doctor to make sure there are no cancer cells in the treated area and no new cancer cells in other parts of the body is absolutely necessary.