Radiotherapy, or radiation therapy, is a form of cancer treatment that uses radiation to shrink tumours or kill cancer cells in a small, targeted area. Radiotherapy most often uses X-rays, but may also involve protons or other types of energy such as gamma rays.
Radiotherapy, chemotherapy and surgery are the 3 most common approaches to treat cancer. They are often used together, such as in concurrent chemo-radiation or in sequence e.g. radiotherapy followed by surgery.
Radiation therapy kills or slows the growth of cells by destroying their DNA. Once the genetic material is damaged, cancer cells stop dividing and start dying.
Radiation therapy takes effect over a period of time. It may take days or weeks of radiation before the cancer cells are destroyed. Even after radiotherapy has ended, the cancer cells will continue to die for weeks or months.
There are 2 main types of radiation therapy.
In external beam radiation therapy, a machine aims radiation at your cancer without contact with your body. It may move around you and direct beams to a specific part of your body from different angles.
External beam radiation therapy includes:
In internal radiation therapy, a source of radiation is placed inside your body. The source of radiation can be:
Your doctor will recommend a suitable type of radiotherapy for your treatment based on factors, including:
While radiotherapy uses high-energy particles or waves to kill cancer cells, chemotherapy uses drugs to treat cancer. Chemotherapy is a systemic treatment as its drugs spread throughout your body, whereas radiotherapy is usually localised at a specific body area.
The difference between radiosurgery and radiotherapy has to do with the intensity and duration of the radiation treatments.
In stereotactic radiosurgery, radiation is delivered at a very high intensity, in one single dose, to a small area.
In stereotactic radiotherapy, radiation is delivered at different times, at lower intensities to larger areas. This allows the healthy tissue time to recover between treatment sessions.
Proton therapy is a newer type of radiotherapy that uses a different energy source. While radiotherapy more commonly uses X-rays, proton therapy uses energy from positively charged particles (protons) to kill cancer cells.
Radiotherapy is used to:
Radiation not only destroys cancerous cells, they also damage healthy cells. Recent radiotherapy techniques such as 3D conformal radiation therapy have reduced this risk by improving the accuracy of beams to target the tumours.
Still, there will be damage to healthy cells and side effects due to the damage. Side effects depend on where your body is exposed to radiation and how much radiation is used.
Below are some of the sides effects for different body parts exposed to radiation.
Any part of the body:
Abdomen:
Brain:
Breasts:
Chest:
Head and neck:
Pelvis and rectum:
Most side effects are manageable and will subside once your treatment has ended.
There is a lifetime dose limit to the amount of radiation an area of your body can safely receive in your lifetime. Your doctor will factor this in when recommending radiotherapy. However, if one area of the body has already reached the limit, another area might still be able to receive radiotherapy if the 2 areas are far apart.
Two Singaporean spin instructors and cancer survivors Rat and Marianne sit down to talk about their healing journeys through diagnosis and treatment at Mount Elizabeth Hospitals and Gleneagles Hospital, and life beyond cancer.
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