Radiation therapy is one of the most common treatments for cancer. Radiation may be used alone or with other treatments, such as surgery, chemotherapy, hormones, or targeted therapy. If your treatment plan includes radiation therapy, knowing how it works and what to expect can often help you prepare for treatment and make informed decisions about your care.
How radiation therapy works against cancer
At high doses, radiation therapy kills cancer cells or slows their growth by damaging their DNA. Cancer cells whose DNA is damaged beyond repair stop dividing or die. When the damaged cells die, they are broken down and removed by the body.
Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before DNA is damaged enough for cancer cells to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends.
Types of radiation therapy
There are two main types of radiation therapy, external beam and internal.
External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions.
External beam radiation therapy is a local treatment, which means it treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.
Learn more about external beam radiation therapy.
Internal radiation therapy is a treatment in which a source of radiation is put inside your body. The radiation source can be solid or liquid.
Internal radiation therapy with a solid source is called brachytherapy. In this type of treatment, seeds, ribbons, or capsules that contain a radiation source are placed in your body, in or near the tumor. Like external beam radiation therapy, brachytherapy is a local treatment and treats only a specific part of your body.
With brachytherapy, the radiation source in your body will give off radiation for a while.
Learn more about brachytherapy.
Internal radiation therapy with a liquid source is called systemic therapy. Systemic means that the treatment travels in the blood to tissues throughout your body, seeking out and killing cancer cells. You receive systemic radiation therapy by swallowing, through a vein via an IV line, or through an injection.
With systemic radiation, your body fluids, such as urine, sweat, and saliva, will give off radiation for a while.
What are the advantages?
- The main advantage of radiotherapy is that it may help to control the growth of the cancer.
- For a small number of people with borderline resectable cancer and locally advanced pancreatic cancer, radiotherapy may help to make surgery possible.
- Each treatment session will take about 30 minutes, or longer for SABR. You won’t usually need to stay in hospital.
- You may be able to carry on with your daily life, such as going to work, if you feel up to it.
- If you have advanced cancer, radiotherapy can help control symptoms and relieve pain.
What are the disadvantages?
- Radiotherapy can cause side effects, including tiredness, sickness and runny poo (diarrhoea).
- If you have chemoradiotherapy, you may get side effects from the chemotherapy. There are ways to manage side effects.
- If you have borderline resectable cancer and locally advanced pancreatic cancer, you may have to go to hospital five days a week for several weeks for your treatment, although this may vary.