Radiation therapy for stomach cancer

Last medical review:

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is sometimes used to treat stomach cancer. Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. You will usually receive other treatments.

Radiation therapy is often combined with chemotherapy to treat stomach cancer. This is called chemoradiation. The 2 treatments are given during the same time period.

Radiation therapy is given for different reasons. You may have radiation therapy or chemoradiation to:

  • destroy the cancer cells in the body
  • shrink a tumour before other treatments such as surgery (called neoadjuvant therapy)
  • destroy cancer cells left behind after surgery or chemotherapy to reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
  • relieve pain or control the symptoms of advanced stomach cancer (called palliative therapy)

External radiation therapy

External radiation therapy (also called external beam radiation therapy) is most commonly used to treat stomach cancer. It uses a machine to direct radiation through the skin to the area with the cancer and some of the tissue around it.

External radiation therapy may be given as a part of chemoradiation before or after surgery to completely remove the cancer. The chemoradiation often includes fluorouracil (also called 5-fluorouracil or 5-FU), which helps make the cancer cells more sensitive to the radiation therapy.

External radiation therapy may be given alone to relieve the symptoms caused by advanced stomach cancer such as bleeding, pain, difficulty swallowing (dysphagia) or a blockage.

External radiation therapy is usually given 5 days a week for several weeks. It may be given for a shorter amount of time when used as palliative therapy.

Side effects

Side effects can happen with any type of treatment for stomach cancer, but everyone's experience is different. Some people have many side effects. Other people have only a few side effects.

During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. But damage to healthy cells can happen and may cause side effects. If you develop side effects, they can happen any time during, immediately after or a few days or weeks after radiation therapy. Sometimes late side effects develop months or years after radiation therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area or organs being treated, the total dose of radiation, the treatment schedule and if radiation therapy is combined with chemotherapy. Some common side effects of radiation therapy and chemoradiation used for stomach cancer are:

Tell your healthcare team if you have these side effects or others you think might be from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Questions to ask about radiation therapy

Find out more about radiation therapy and side effects of radiation therapy. To make the decisions that are right for you, ask your healthcare team questions about radiation therapy.

Expert review and references

  • American Cancer Society . Treating Stomach Cancer . 2017 : https://www.cancer.org/.
  • American Society of Clinical Oncology (ASCO) . Cancer.Net: Stomach Cancer. 2020: https://www.cancer.net/.
  • National Comprehensive Cancer Network . NCCN Clinical Practice Guidelines in Oncology: Gastric Cancer (Version 1.2019). https://www.nccn.org/home.
  • National Cancer Institute. Gastric Cancer Treatment (PDQ®)–Health Professional Version. National Institutes of Health; 2018: https://www.cancer.gov/.
  • National Cancer Institute. Gastric Cancer Treatment (PDQ®)–Patient Version. National Institutes of Health; 2018: https://www.cancer.gov/.
  • Alberta Health Services. Clinical Practice Guideline GI-008 Version 4: Gastric Cancer. Edmonton, AB: 2016: https://www.albertahealthservices.ca/.

Medical disclaimer

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