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Radiation Therapy for Stomach Cancer

Radiation therapy uses high-energy rays or particles to kill cancer cells in a specific part of the body.

When is radiation therapy used?

Radiation can be used in different ways to help treat stomach cancer (gastric cancer):

  • For some earlier stage cancers, radiation can be used along with chemotherapy (chemo) before surgery to try to shrink the cancer and make it easier to remove. (This combination is known as chemoradiation.)
  • After surgery, radiation therapy can be used along with chemo to try to kill any cancer cells that weren't removed during the surgery. This may help delay or prevent recurrence of the cancer.
  • For cancers that can't be removed by surgery, radiation therapy can sometimes be used to help slow the growth of the cancer and ease symptoms, such as pain, bleeding, or eating problems.

How is radiation therapy given?

When radiation therapy is used to treat stomach cancer, the radiation is focused on the cancer from a machine outside the body. Often, special types of radiation therapy, such three-dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) are used. These approaches use computers to aim the radiation at the cancer from several angles (as well as other special techniques). This can help focus the radiation on the cancer and limit the damage to nearby normal tissues.

Before your treatments start, the radiation team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. This planning session, called simulation, usually includes getting imaging tests such as CT or MRI scans.

Radiation therapy is much like getting an x-ray, but the radiation is much stronger. The treatment itself is painless. Each treatment lasts only a few minutes, although the setup time — getting you into place for treatment — usually takes longer. Treatments are usually given 5 days a week over at least several weeks, but the length of treatment depends on the reason it’s being given.

Possible side effects of radiation therapy

Side effects from radiation therapy for stomach cancer can include:

  • Skin problems, ranging from redness to blistering and peeling, in areas the radiation passed through
  • Nausea and vomiting
  • Diarrhea
  • Fatigue
  • Low blood cell counts

These usually go away within a few weeks after the treatment is finished.

When radiation is given with chemotherapy, side effects are often worse.

Some people may have problems eating and getting enough fluids during and after treatment. Some might need to have fluids given into a vein (IV) or have a feeding tube placed to get nutrition during treatment. If the tube is only needed for a short time, one can be passed down the nose and throat and into the stomach or intestine. If the tube is needed for a longer time, it can be placed through the skin in the abdomen and into the intestine during a surgical procedure. This is known as a jejunostomy tube or J-tube. Liquid nutrition can then be put directly into the tube.

Be sure to tell your doctor about any side effects you have, because there are often ways to relieve them.

Radiation might also damage nearby organs. This could lead to problems such as heart or lung damage, or even an increased risk of another cancer later on. Doctors do their best to prevent this by using only the needed dose of radiation, carefully controlling where the beams are aimed, and shielding certain parts of the body from the radiation during treatment.

More information about radiation therapy

To learn more about how radiation is used to treat cancer, see Radiation Therapy.

To learn about some of the side effects listed here and how to manage them, see Managing Cancer-related Side Effects.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

Bendell J. Local palliation for advanced gastric cancer. UpToDate. 2020. Accessed at on July 14, 2020.

Ku GY, Ilson DH. Chapter 72: Cancer of the Stomach. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.

Mamon H, Enzinger PC. Adjuvant and neoadjuvant treatment of gastric cancer. UpToDate. 2020. Accessed at on July 14, 2020.

National Cancer Institute. Physician Data Query (PDQ). Gastric Cancer Treatment. 2020. Accessed at: on July 14, 2020.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Gastric Cancer. Version 2.2020. Accessed at on July 14, 2020.

Last Revised: January 22, 2021

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