When Eating is Difficult Although cancer treatment is aimed at destroying cancer cells, it may cause side effects that produce eating problems. Many factors will determine what side effects you experience during treatment, including the type of treatment you are receiving, the length of treatment, and what part of the body is being treated. Click on the links below for more information Surgery Radiation Therapy Chemotherapy Surgery Although when you have surgery you need good nutrition, the stress of surgery may slow digestion. It may also be difficult to eat because your mouth, throat, and stomach may be sore or may not be working properly. Radiation Therapy Radiation therapy damages cancer cells as well as healthy cells. If you have treatment to the head, neck, or chest, you may experience dry mouth, sore mouth, sore throat, difficulty swallowing, a change in the way food tastes, and dental problems. If you have treatment of the stomach, you may experience nausea, vomiting, and diarrhea. Chemotherapy Chemotherapy destroys cancer cells, but may also affect parts of the body needed for eating. You may experience nausea and vomiting, loss of appetite, diarrhea, constipation, sore mouth and throat, weight gain, and changes in the way food tastes.