Radiation treatment is often used to treat cancer that has spread to the abdomen. It can be very effective at relieving symptoms such as pain, but the radiotherapy itself can cause side-effects such as cramping and diarrhea. This study will investigate whether it is possible to reduce the unwanted side-effects of radiotherapy with a new technology called "helical tomotherapy". Tomotherapy is a new way to deliver radiation in a much more accurate fashion than is currently done, and with less radiation being delivered to normal tissues around the tumor. This study will involve the treatment of 20 patients, who have a spread of their cancer within the abdomen and pelvis, using helical tomotherapy. The dose and energy of radiation will be the same as is currently used - only the delivery system is different. The purpose is to assure that tomotherapy is a safe way to deliver radiation treatment and to investigate whether it will reduce the toxicity of radiation treatment in these patients. Patients will be treated in groups of three until all 20 have been treated. The toxicity of treatment will be measured with a questionnaire for each one. If any unexpected severe treatment complications occur, further accrual will stop.