In people with cancer, swelling of the stomach or abdominal area can have a few different causes.

• Fluid may collect in the area of the body containing the abdominal organs. This fluid is called ascites. It may result from the tumor causing the body to produce more fluid, or the tumor may be blocking the normal flow of fluid through the lymph and other body systems. Ascites can make someone feel bloated, uncomfortable and short of breath. If this does not bother the patient, it can be left alone. If there is discomfort, then the fluid sometimes can be drained. The draining of ascites from the abdominal cavity is called paracentesis. At times, medications can help the body eliminate the fluid. The medications often are not that helpful, because it’s not that there is too much fluid in the body, rather it is just collecting in the wrong places.
   
• Sometimes the bowels do not empty well. Stool may build up and gas may cause bloating. This can be due to constipation from opioids, from a general slowing of the bowels due to weakness, or a blockage of the bowel due to a tumor. In all these cases the patient usually has symptoms of constipation. Constipation from medication or slowed bowels can be treated with laxatives.
   
• As some illnesses progress, there can be swelling under the skin and in other body tissues. This is called edema.

Sometimes the causes of swelling can be treated and swelling decreased. For example, bowel functioning may be improved if a blockage is removed. At other times the cause of the swelling can’t be treated and it’s best to treat the symptoms associated with it. For example, if the swelling is causing shortness of breath, there are medications to ease this.