Radiotherapy is not usually used to treat cancer of the stomach. This is because the stomach is so close to other major organs that it is difficult to give effective treatment without damaging the other organs. The doses that would be necessary to try to cure the cancer would cause many side effects.

In the situation where the cancer has spread beyond the stomach and is causing pain, a small dose of radiotherapy may be very helpful to relieve pain.

In some situations chemotherapy and radiotherapy may be given at the same time. This is known as chemo-radiotherapy and it is sometimes given after surgery. Chemo-radiotherapy in the treatment of stomach cancer is still being researched in clinical trials.